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SELECT 
  pfv.feature_id, 
  pfv.product_id, 
  pfv.variant_id, 
  gp.group_id 
FROM 
  cscart_product_features_values AS pfv 
  INNER JOIN cscart_product_variation_group_products AS gp ON pfv.product_id = gp.product_id 
  INNER JOIN cscart_product_variation_group_features AS gpf ON gpf.group_id = gp.group_id 
  AND gpf.feature_id = pfv.feature_id 
WHERE 
  pfv.lang_code = 'ja' 
  AND gp.group_id IN (
    49, 25, 19, 32, 37, 34, 39, 47, 43, 29, 52, 
    33, 53, 45
  )

Query time 0.01007

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "gpf",
      "access_type": "index",
      "possible_keys": ["PRIMARY", "idx_group_id"],
      "key": "PRIMARY",
      "key_length": "6",
      "used_key_parts": ["feature_id", "group_id"],
      "rows": 46,
      "filtered": 100,
      "using_index": true
    },
    "table": {
      "table_name": "pfv",
      "access_type": "ref",
      "possible_keys": [
        "PRIMARY",
        "fl",
        "lang_code",
        "product_id",
        "fpl",
        "idx_product_feature_variant_id"
      ],
      "key": "PRIMARY",
      "key_length": "3",
      "used_key_parts": ["feature_id"],
      "ref": ["cscart_purchase_fl_com.gpf.feature_id"],
      "rows": 3,
      "filtered": 58.7939682,
      "attached_condition": "pfv.lang_code = 'ja'",
      "using_index": true
    },
    "table": {
      "table_name": "gp",
      "access_type": "eq_ref",
      "possible_keys": ["PRIMARY", "idx_group_id"],
      "key": "PRIMARY",
      "key_length": "6",
      "used_key_parts": ["product_id", "group_id"],
      "ref": [
        "cscart_purchase_fl_com.pfv.product_id",
        "cscart_purchase_fl_com.gpf.group_id"
      ],
      "rows": 1,
      "filtered": 100,
      "attached_condition": "gp.group_id in (49,25,19,32,37,34,39,47,43,29,52,33,53,45)",
      "using_index": true
    }
  }
}

Result

feature_id	product_id	variant_id	group_id
7	136	18	19
7	179	19	19
7	180	20	19
7	139	18	25
7	191	19	25
7	192	20	25
7	135	18	29
7	200	18	29
7	201	19	29
7	202	19	29
7	203	20	29
7	204	20	29
7	111	18	32
7	211	19	32
7	212	20	32
7	213	18	32
7	214	19	32
7	215	20	32
7	216	18	32
7	217	19	32
7	218	20	32
7	134	18	33
7	219	18	33
7	220	19	33
7	221	19	33
7	222	20	33
7	223	20	33
7	125	18	34
7	224	19	34
7	225	20	34
7	177	18	37
7	233	19	37
7	234	20	37
7	129	18	39
7	237	19	39
7	238	20	39
7	128	18	43
7	256	19	43
7	257	20	43
7	137	18	45
7	260	19	45
7	261	20	45
7	262	18	45
7	263	19	45
7	264	20	45
7	131	18	47
7	273	19	47
7	274	20	47
7	133	18	49
7	277	19	49
7	278	20	49
7	132	18	52
7	283	19	52
7	284	20	52
7	127	18	53
7	285	19	53
7	286	20	53
8	135	26	29
8	200	27	29
8	201	26	29
8	202	27	29
8	203	26	29
8	204	27	29
8	134	26	33
8	219	27	33
8	220	26	33
8	221	27	33
8	222	26	33
8	223	27	33
9	111	29	32
9	211	29	32
9	212	29	32
9	213	34	32
9	214	34	32
9	215	34	32
9	216	36	32
9	217	36	32
9	218	36	32
9	137	29	45
9	260	29	45
9	261	29	45
9	262	31	45
9	263	31	45
9	264	31	45

feature_id	product_id	variant_id	group_id
7	136	18	19
7	179	19	19
7	180	20	19
7	139	18	25
7	191	19	25
7	192	20	25
7	135	18	29
7	200	18	29
7	201	19	29
7	202	19	29
7	203	20	29
7	204	20	29
7	111	18	32
7	211	19	32
7	212	20	32
7	213	18	32
7	214	19	32
7	215	20	32
7	216	18	32
7	217	19	32
7	218	20	32
7	134	18	33
7	219	18	33
7	220	19	33
7	221	19	33
7	222	20	33
7	223	20	33
7	125	18	34
7	224	19	34
7	225	20	34
7	177	18	37
7	233	19	37
7	234	20	37
7	129	18	39
7	237	19	39
7	238	20	39
7	128	18	43
7	256	19	43
7	257	20	43
7	137	18	45
7	260	19	45
7	261	20	45
7	262	18	45
7	263	19	45
7	264	20	45
7	131	18	47
7	273	19	47
7	274	20	47
7	133	18	49
7	277	19	49
7	278	20	49
7	132	18	52
7	283	19	52
7	284	20	52
7	127	18	53
7	285	19	53
7	286	20	53
8	135	26	29
8	200	27	29
8	201	26	29
8	202	27	29
8	203	26	29
8	204	27	29
8	134	26	33
8	219	27	33
8	220	26	33
8	221	27	33
8	222	26	33
8	223	27	33
9	111	29	32
9	211	29	32
9	212	29	32
9	213	34	32
9	214	34	32
9	215	34	32
9	216	36	32
9	217	36	32
9	218	36	32
9	137	29	45
9	260	29	45
9	261	29	45
9	262	31	45
9	263	31	45
9	264	31	45

feature_id	product_id	variant_id	group_id
7	136	18	19
7	179	19	19
7	180	20	19
7	139	18	25
7	191	19	25
7	192	20	25
7	135	18	29
7	200	18	29
7	201	19	29
7	202	19	29
7	203	20	29
7	204	20	29
7	111	18	32
7	211	19	32
7	212	20	32
7	213	18	32
7	214	19	32
7	215	20	32
7	216	18	32
7	217	19	32
7	218	20	32
7	134	18	33
7	219	18	33
7	220	19	33
7	221	19	33
7	222	20	33
7	223	20	33
7	125	18	34
7	224	19	34
7	225	20	34
7	177	18	37
7	233	19	37
7	234	20	37
7	129	18	39
7	237	19	39
7	238	20	39
7	128	18	43
7	256	19	43
7	257	20	43
7	137	18	45
7	260	19	45
7	261	20	45
7	262	18	45
7	263	19	45
7	264	20	45
7	131	18	47
7	273	19	47
7	274	20	47
7	133	18	49
7	277	19	49
7	278	20	49
7	132	18	52
7	283	19	52
7	284	20	52
7	127	18	53
7	285	19	53
7	286	20	53
8	135	26	29
8	200	27	29
8	201	26	29
8	202	27	29
8	203	26	29
8	204	27	29
8	134	26	33
8	219	27	33
8	220	26	33
8	221	27	33
8	222	26	33
8	223	27	33
9	111	29	32
9	211	29	32
9	212	29	32
9	213	34	32
9	214	34	32
9	215	34	32
9	216	36	32
9	217	36	32
9	218	36	32
9	137	29	45
9	260	29	45
9	261	29	45
9	262	31	45
9	263	31	45
9	264	31	45

feature_id	product_id	variant_id	group_id
7	136	18	19
7	179	19	19
7	180	20	19
7	139	18	25
7	191	19	25
7	192	20	25
7	135	18	29
7	200	18	29
7	201	19	29
7	202	19	29
7	203	20	29
7	204	20	29
7	111	18	32
7	211	19	32
7	212	20	32
7	213	18	32
7	214	19	32
7	215	20	32
7	216	18	32
7	217	19	32
7	218	20	32
7	134	18	33
7	219	18	33
7	220	19	33
7	221	19	33
7	222	20	33
7	223	20	33
7	125	18	34
7	224	19	34
7	225	20	34
7	177	18	37
7	233	19	37
7	234	20	37
7	129	18	39
7	237	19	39
7	238	20	39
7	128	18	43
7	256	19	43
7	257	20	43
7	137	18	45
7	260	19	45
7	261	20	45
7	262	18	45
7	263	19	45
7	264	20	45
7	131	18	47
7	273	19	47
7	274	20	47
7	133	18	49
7	277	19	49
7	278	20	49
7	132	18	52
7	283	19	52
7	284	20	52
7	127	18	53
7	285	19	53
7	286	20	53
8	135	26	29
8	200	27	29
8	201	26	29
8	202	27	29
8	203	26	29
8	204	27	29
8	134	26	33
8	219	27	33
8	220	26	33
8	221	27	33
8	222	26	33
8	223	27	33
9	111	29	32
9	211	29	32
9	212	29	32
9	213	34	32
9	214	34	32
9	215	34	32
9	216	36	32
9	217	36	32
9	218	36	32
9	137	29	45
9	260	29	45
9	261	29	45
9	262	31	45
9	263	31	45
9	264	31	45