SELECT 
  product_id, 
  group_id 
FROM 
  cscart_product_variation_group_products 
WHERE 
  group_id IN (
    666, 648, 673, 689, 665, 676, 688, 649, 
    634, 555, 684, 662, 953, 683
  )

Query time 0.00057

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "41.76"
    },
    "table": {
      "table_name": "cscart_product_variation_group_products",
      "access_type": "range",
      "possible_keys": [
        "idx_group_id"
      ],
      "key": "idx_group_id",
      "used_key_parts": [
        "group_id"
      ],
      "key_length": "3",
      "rows_examined_per_scan": 85,
      "rows_produced_per_join": 85,
      "filtered": "100.00",
      "index_condition": "(`softwarepirmam_hewadelivard_cscart_4`.`cscart_product_variation_group_products`.`group_id` in (666,648,673,689,665,676,688,649,634,555,684,662,953,683))",
      "cost_info": {
        "read_cost": "33.26",
        "eval_cost": "8.50",
        "prefix_cost": "41.76",
        "data_read_per_join": "1K"
      },
      "used_columns": [
        "product_id",
        "group_id"
      ]
    }
  }
}

Result

product_id group_id
4941 555
4940 555
4939 555
4935 555
5815 634
5816 634
5948 648
6128 648
6127 648
6126 648
6129 648
6130 648
6131 648
6132 648
6133 648
6134 648
6135 648
5952 649
6138 649
6137 649
6136 649
6139 649
6140 649
6141 649
6142 649
6143 649
6031 662
6032 662
6033 662
6034 662
6035 662
6048 665
6049 665
6050 665
6051 665
6052 665
6053 665
6054 666
6055 666
6056 666
6057 666
6058 666
6059 666
5956 673
6087 673
6088 673
6089 673
6090 673
6091 673
6092 673
6093 673
6101 676
6102 676
6103 676
6104 676
6105 676
6106 676
6107 676
6108 676
6109 676
6164 683
6165 683
6166 683
6167 683
6168 683
6169 683
6170 683
6171 684
6172 684
6173 684
6174 684
6175 684
6176 684
6177 684
5804 688
6193 688
6196 689
6195 689
6194 689
6197 689
6198 689
6199 689
6200 689
6201 689
6202 689
10089 953