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 (
    260, 340, 410, 169, 354, 372, 219, 284, 
    195, 306, 349, 305, 409, 171, 307, 118, 
    348, 261, 350, 120, 351, 341, 282, 352, 
    346
  )

Query time 0.00150

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "70.01"
    },
    "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": 25,
          "rows_produced_per_join": 25,
          "filtered": "100.00",
          "index_condition": "(`softwarepirmam_hewadelivard_cscart_4`.`gpf`.`group_id` in (260,340,410,169,354,372,219,284,195,306,349,305,409,171,307,118,348,261,350,120,351,341,282,352,346))",
          "cost_info": {
            "read_cost": "15.01",
            "eval_cost": "2.50",
            "prefix_cost": "17.51",
            "data_read_per_join": "2K"
          },
          "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": 75,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "18.75",
            "eval_cost": "7.50",
            "prefix_cost": "43.76",
            "data_read_per_join": "1K"
          },
          "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": 75,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "18.75",
            "eval_cost": "7.50",
            "prefix_cost": "70.01",
            "data_read_per_join": "58K"
          },
          "used_columns": [
            "feature_id",
            "product_id",
            "variant_id",
            "lang_code"
          ]
        }
      }
    ]
  }
}

Result

feature_id product_id variant_id group_id
656 1600 1560 118
656 1601 1559 118
656 1602 1557 118
656 1603 1558 118
656 1609 1560 120
656 1610 1559 120
656 2314 1610 169
656 2312 1560 169
656 2310 1776 169
656 2334 1559 171
656 2333 1560 171
656 2430 1560 195
656 2431 1559 195
656 2559 1560 219
656 2560 1559 219
656 3663 1596 219
656 2698 2985 260
656 2702 1560 261
656 2703 2993 261
656 2805 1560 282
656 2808 1559 282
656 2822 1560 284
656 2823 1559 284
656 2824 1755 284
656 2825 1682 284
656 2826 1558 284
656 2922 1560 305
656 2923 1559 305
656 2924 1560 306
656 2925 1559 306
656 2927 1560 307
656 2928 1559 307
656 2929 1600 307
656 2930 1609 307
656 3090 1560 340
656 3091 1559 340
656 3092 1596 340
656 3093 1600 340
656 3094 1558 340
656 3096 1560 341
656 3097 1559 341
656 3098 2315 341
656 3114 1560 346
656 3115 1559 346
656 3131 1560 348
656 3132 1559 348
656 3133 1600 348
656 3136 1560 349
656 3137 1559 349
656 3138 1783 349
656 3140 1560 350
656 3141 1559 350
656 3142 1560 351
656 3143 1596 351
656 3144 1600 351
656 3150 1560 352
656 3151 1559 352
656 3155 1560 354
656 3156 1559 354
656 2737 1560 372
656 3255 1559 372
656 3604 1559 409
656 3603 1560 409
656 3605 1560 410
656 3606 1559 410