SELECT 
  pfv.feature_id, 
  pfv.product_id, 
  pfv.variant_id, 
  gp.group_id 
FROM 
  cscart_product_features_values AS pfv 
  INNER JOIN cscart_product_variation_group_products AS gp ON pfv.product_id = gp.product_id 
  INNER JOIN cscart_product_variation_group_features AS gpf ON gpf.group_id = gp.group_id 
  AND gpf.feature_id = pfv.feature_id 
WHERE 
  pfv.lang_code = 'en' 
  AND gp.group_id IN (
    275, 274, 356, 273, 272, 271, 270, 372, 
    268, 267, 266, 265, 263, 262, 261
  )

Query time 0.00129

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "42.01"
    },
    "nested_loop": [
      {
        "table": {
          "table_name": "gpf",
          "access_type": "range",
          "possible_keys": [
            "PRIMARY",
            "idx_group_id"
          ],
          "key": "idx_group_id",
          "used_key_parts": [
            "group_id"
          ],
          "key_length": "3",
          "rows_examined_per_scan": 15,
          "rows_produced_per_join": 15,
          "filtered": "100.00",
          "index_condition": "(`softwarepirmam_hewadelivard_cscart_4`.`gpf`.`group_id` in (275,274,356,273,272,271,270,372,268,267,266,265,263,262,261))",
          "cost_info": {
            "read_cost": "9.01",
            "eval_cost": "1.50",
            "prefix_cost": "10.51",
            "data_read_per_join": "1K"
          },
          "used_columns": [
            "feature_id",
            "group_id"
          ]
        }
      },
      {
        "table": {
          "table_name": "gp",
          "access_type": "ref",
          "possible_keys": [
            "PRIMARY",
            "idx_group_id"
          ],
          "key": "idx_group_id",
          "used_key_parts": [
            "group_id"
          ],
          "key_length": "3",
          "ref": [
            "softwarepirmam_hewadelivard_cscart_4.gpf.group_id"
          ],
          "rows_examined_per_scan": 3,
          "rows_produced_per_join": 45,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "11.25",
            "eval_cost": "4.50",
            "prefix_cost": "26.26",
            "data_read_per_join": "720"
          },
          "used_columns": [
            "product_id",
            "group_id"
          ]
        }
      },
      {
        "table": {
          "table_name": "pfv",
          "access_type": "ref",
          "possible_keys": [
            "PRIMARY",
            "fl",
            "lang_code",
            "product_id",
            "fpl",
            "idx_product_feature_variant_id"
          ],
          "key": "fpl",
          "used_key_parts": [
            "feature_id",
            "product_id",
            "lang_code"
          ],
          "key_length": "12",
          "ref": [
            "softwarepirmam_hewadelivard_cscart_4.gpf.feature_id",
            "softwarepirmam_hewadelivard_cscart_4.gp.product_id",
            "const"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 45,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "11.25",
            "eval_cost": "4.50",
            "prefix_cost": "42.01",
            "data_read_per_join": "34K"
          },
          "used_columns": [
            "feature_id",
            "product_id",
            "variant_id",
            "lang_code"
          ]
        }
      }
    ]
  }
}

Result

feature_id product_id variant_id group_id
656 2702 1560 261
656 2703 2993 261
656 2704 2315 262
656 2705 1596 262
656 2706 1600 262
656 2708 1560 263
656 2709 1600 263
656 2710 2315 263
656 2714 1609 265
656 2715 1559 265
656 2716 1560 265
656 2717 2308 265
656 2719 1600 266
656 2728 2993 266
656 2723 1560 267
656 2724 1559 267
656 2725 1609 267
656 2726 1783 267
656 2729 1560 268
656 2730 1559 268
656 2731 1600 268
656 2732 1558 268
656 2739 1600 270
656 2740 1559 270
656 2741 1558 270
656 2742 1560 271
656 2743 1559 271
656 2744 1600 271
656 2745 1609 271
656 2746 1559 272
656 2747 1609 272
656 2749 1560 272
656 2750 1724 272
656 2751 1783 272
656 2752 1724 273
656 2753 1559 273
656 2754 1560 273
656 2755 1609 273
656 2756 1783 273
656 2757 2444 273
656 2761 1558 274
656 2762 1559 274
656 2763 1560 274
656 2764 1783 274
656 2768 1558 275
656 2767 1560 275
656 2760 1560 356
656 3164 1559 356
656 3165 1783 356
656 2737 1560 372
656 3255 1559 372