SELECT 
  product_id, 
  group_id 
FROM 
  cscart_product_variation_group_products 
WHERE 
  group_id IN (
    49, 25, 19, 32, 37, 34, 39, 47, 43, 29, 52, 
    33, 53, 45
  )

Query time 0.00030

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_product_variation_group_products",
      "access_type": "index",
      "possible_keys": ["idx_group_id"],
      "key": "PRIMARY",
      "key_length": "6",
      "used_key_parts": ["product_id", "group_id"],
      "rows": 126,
      "filtered": 47.61904907,
      "attached_condition": "cscart_product_variation_group_products.group_id in (49,25,19,32,37,34,39,47,43,29,52,33,53,45)",
      "using_index": true
    }
  }
}

Result

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