Sandbox

SELECT 
  product_id, 
  group_id 
FROM 
  cscart_product_variation_group_products 
WHERE 
  group_id IN (36, 35, 34, 37, 106, 108, 52, 102, 103)

Query time 0.00036

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "32.81"
    },
    "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": 17,
      "rows_produced_per_join": 17,
      "filtered": "100.00",
      "index_condition": "(`cscart`.`cscart_product_variation_group_products`.`group_id` in (36,35,34,37,106,108,52,102,103))",
      "cost_info": {
        "read_cost": "29.41",
        "eval_cost": "3.40",
        "prefix_cost": "32.81",
        "data_read_per_join": "272"
      },
      "used_columns": [
        "product_id",
        "group_id"
      ]
    }
  }
}

Result

product_id	group_id
599	34
600	34
601	35
602	35
603	36
604	36
605	37
606	37
675	52
676	52
677	52
912	102
911	102
917	103
916	103
915	103
914	103
923	106
922	106
931	108
930	108
929	108
928	108
927	108
926	108

product_id	group_id
599	34
600	34
601	35
602	35
603	36
604	36
605	37
606	37
675	52
676	52
677	52
912	102
911	102
917	103
916	103
915	103
914	103
923	106
922	106
931	108
930	108
929	108
928	108
927	108
926	108

product_id	group_id
599	34
600	34
601	35
602	35
603	36
604	36
605	37
606	37
675	52
676	52
677	52
912	102
911	102
917	103
916	103
915	103
914	103
923	106
922	106
931	108
930	108
929	108
928	108
927	108
926	108

product_id	group_id
599	34
600	34
601	35
602	35
603	36
604	36
605	37
606	37
675	52
676	52
677	52
912	102
911	102
917	103
916	103
915	103
914	103
923	106
922	106
931	108
930	108
929	108
928	108
927	108
926	108