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 (1063, 1055, 1054)

Query time 0.00164

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "38.68"
    },
    "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": 8,
          "rows_produced_per_join": 8,
          "filtered": "100.00",
          "index_condition": "(`cscart_db`.`gpf`.`group_id` in (1063,1055,1054))",
          "cost_info": {
            "read_cost": "3.56",
            "eval_cost": "0.80",
            "prefix_cost": "4.36",
            "data_read_per_join": "832"
          },
          "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": [
            "cscart_db.gpf.group_id"
          ],
          "rows_examined_per_scan": 4,
          "rows_produced_per_join": 32,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "8.00",
            "eval_cost": "3.20",
            "prefix_cost": "15.56",
            "data_read_per_join": "512"
          },
          "used_columns": [
            "product_id",
            "group_id"
          ]
        }
      },
      {
        "table": {
          "table_name": "pfv",
          "access_type": "ref",
          "possible_keys": [
            "PRIMARY",
            "lang_code",
            "product_id",
            "fpl",
            "idx_product_feature_variant_id",
            "fl"
          ],
          "key": "idx_product_feature_variant_id",
          "used_key_parts": [
            "product_id",
            "feature_id",
            "lang_code"
          ],
          "key_length": "12",
          "ref": [
            "cscart_db.gp.product_id",
            "cscart_db.gpf.feature_id",
            "const"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 39,
          "filtered": "100.00",
          "using_index": true,
          "cost_info": {
            "read_cost": "19.21",
            "eval_cost": "3.91",
            "prefix_cost": "38.68",
            "data_read_per_join": "1K"
          },
          "used_columns": [
            "feature_id",
            "product_id",
            "variant_id",
            "lang_code"
          ]
        }
      }
    ]
  }
}

Result

feature_id product_id variant_id group_id
74 65173 19150 1054
74 65172 19150 1054
74 65171 19150 1054
63 65173 10348 1054
63 65172 10348 1054
63 65171 10348 1054
102 65173 62256 1054
102 65172 62266 1054
102 65171 62257 1054
102 65175 62257 1055
102 65174 62268 1055
63 65175 10348 1055
63 65174 10348 1055
74 65175 19150 1055
74 65174 19150 1055
63 66749 10351 1063
63 66748 10351 1063
63 66743 10351 1063
63 66747 10351 1063
63 66756 10351 1063
63 66746 10351 1063
63 66745 10351 1063
63 66744 10351 1063
63 66742 10351 1063
63 66775 10351 1063
63 66776 10351 1063
63 66777 10351 1063
63 66778 10351 1063
63 66779 10351 1063
63 66780 10351 1063
63 66781 10351 1063
63 66740 10351 1063
63 66739 10351 1063
63 66738 10351 1063
63 66737 10351 1063
63 66736 10351 1063
63 66735 10351 1063
63 66734 10351 1063
63 66733 10351 1063
63 66732 10351 1063
63 66731 10351 1063
63 66730 10351 1063
63 66729 10351 1063
63 66741 10351 1063
63 66728 10351 1063
63 66773 10351 1063
63 66770 10351 1063
63 66769 10351 1063
63 66771 10351 1063
63 66768 10351 1063
63 66767 10351 1063
63 66766 10351 1063
63 66765 10351 1063
63 66763 10351 1063
63 66762 10351 1063
63 66764 10351 1063
63 66761 10351 1063
63 66760 10351 1063
63 66772 10351 1063
63 66727 10351 1063
63 66757 10351 1063
63 66759 10351 1063
63 66785 10351 1063
63 66784 10351 1063
63 66774 10351 1063
63 66758 10351 1063
63 66786 10351 1063
63 66755 10351 1063
63 66754 10351 1063
63 66753 10351 1063
63 66752 10351 1063
63 66751 10351 1063
63 66750 10351 1063
63 66783 10351 1063
63 66782 10351 1063
104 66749 62350 1063
104 66748 62349 1063
104 66743 62347 1063
104 66747 62349 1063
104 66756 62354 1063
104 66746 62348 1063
104 66745 62348 1063
104 66744 62347 1063
104 66742 62346 1063
104 66775 62362 1063
104 66776 62362 1063
104 66777 62363 1063
104 66778 62363 1063
104 66779 62052 1063
104 66780 62052 1063
104 66781 62364 1063
104 66740 62345 1063
104 66739 62345 1063
104 66738 62344 1063
104 66737 62344 1063
104 66736 62343 1063
104 66735 62343 1063
104 66734 62342 1063
104 66733 62342 1063
104 66732 62341 1063
104 66731 62341 1063
104 66730 62340 1063
104 66729 62340 1063
104 66741 62346 1063
104 66728 62339 1063
104 66773 62361 1063
104 66770 62359 1063
104 66769 62359 1063
104 66771 62360 1063
104 66768 62054 1063
104 66767 62054 1063
104 66766 62053 1063
104 66765 62053 1063
104 66763 62358 1063
104 66762 62357 1063
104 66764 62358 1063
104 66761 62357 1063
104 66760 62356 1063
104 66772 62360 1063
104 66727 62339 1063
104 66757 62355 1063
104 66759 62356 1063
104 66785 62366 1063
104 66784 62365 1063
104 66774 62361 1063
104 66758 62051 1063
104 66786 62366 1063
104 66755 62354 1063
104 66754 62353 1063
104 66753 62352 1063
104 66752 62351 1063
104 66751 62351 1063
104 66750 62350 1063
104 66783 62365 1063
104 66782 62364 1063
67 66749 41509 1063
67 66748 19983 1063
67 66743 41509 1063
67 66747 41509 1063
67 66756 19983 1063
67 66746 19983 1063
67 66745 41509 1063
67 66744 19983 1063
67 66742 19983 1063
67 66775 41509 1063
67 66776 19983 1063
67 66777 41509 1063
67 66778 19983 1063
67 66779 41509 1063
67 66780 19983 1063
67 66781 41509 1063
67 66740 19983 1063
67 66739 41509 1063
67 66738 19983 1063
67 66737 41509 1063
67 66736 19983 1063
67 66735 41509 1063
67 66734 19983 1063
67 66733 41509 1063
67 66732 19983 1063
67 66731 41509 1063
67 66730 19983 1063
67 66729 41509 1063
67 66741 41509 1063
67 66728 19983 1063
67 66773 41509 1063
67 66770 19983 1063
67 66769 41509 1063
67 66771 41509 1063
67 66768 19983 1063
67 66767 41509 1063
67 66766 19983 1063
67 66765 41509 1063
67 66763 41509 1063
67 66762 19983 1063
67 66764 19983 1063
67 66761 41509 1063
67 66760 19983 1063
67 66772 19983 1063
67 66727 41509 1063
67 66757 41509 1063
67 66759 41509 1063
67 66785 41509 1063
67 66784 19983 1063
67 66774 19983 1063
67 66758 19983 1063
67 66786 19983 1063
67 66755 41509 1063
67 66754 19983 1063
67 66753 41509 1063
67 66752 19983 1063
67 66751 41509 1063
67 66750 19983 1063
67 66783 41509 1063
67 66782 19983 1063