SELECT 
  product_id, 
  group_id 
FROM 
  cscart_product_variation_group_products 
WHERE 
  group_id IN (87, 90, 82, 86, 89, 85, 92, 88, 93)

Query time 0.00050

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "52.41"
    },
    "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": 31,
      "rows_produced_per_join": 31,
      "filtered": "100.00",
      "index_condition": "(`cscart`.`cscart_product_variation_group_products`.`group_id` in (87,90,82,86,89,85,92,88,93))",
      "cost_info": {
        "read_cost": "46.21",
        "eval_cost": "6.20",
        "prefix_cost": "52.41",
        "data_read_per_join": "496"
      },
      "used_columns": [
        "product_id",
        "group_id"
      ]
    }
  }
}

Result

product_id group_id
831 82
830 82
829 82
828 82
827 82
841 85
840 85
839 85
838 85
837 85
846 86
845 86
844 86
843 86
842 86
851 87
850 87
849 87
848 87
847 87
853 88
852 88
858 89
857 89
856 89
855 89
854 89
863 90
862 90
861 90
860 90
859 90
872 92
871 92
870 92
869 92
868 92
874 93
873 93