SELECT 
  product_id, 
  group_id 
FROM 
  cscart_product_variation_group_products 
WHERE 
  group_id IN (
    54, 49, 25, 51, 19, 50, 55, 48, 35, 13, 32, 
    27, 57, 20, 44, 21, 37, 26, 34, 39, 47
  )

Query time 0.00034

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": 55.55555725,
      "attached_condition": "cscart_product_variation_group_products.group_id in (54,49,25,51,19,50,55,48,35,13,32,27,57,20,44,21,37,26,34,39,47)",
      "using_index": true
    }
  }
}

Result

product_id group_id
111 32
113 51
115 50
125 34
129 39
131 47
133 49
136 19
139 25
140 26
141 13
142 44
143 35
144 48
145 54
146 21
147 27
148 55
149 20
150 57
158 13
159 13
177 37
179 19
180 19
181 20
182 20
183 21
184 21
191 25
192 25
193 26
194 26
195 27
196 27
211 32
212 32
213 32
214 32
215 32
216 32
217 32
218 32
224 34
225 34
226 35
227 35
233 37
234 37
237 39
238 39
258 44
259 44
273 47
274 47
275 48
276 48
277 49
278 49
279 50
280 50
281 51
282 51
287 54
288 54
289 55
290 55
293 57
294 57