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 = 'ru' 
  AND gp.group_id IN (
    46, 119, 120, 128, 44, 39, 40, 132, 133, 
    129
  )

Query time 0.00075

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "96.01"
    },
    "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": 10,
          "rows_produced_per_join": 10,
          "filtered": "100.00",
          "index_condition": "(`cscart`.`gpf`.`group_id` in (46,119,120,128,44,39,40,132,133,129))",
          "cost_info": {
            "read_cost": "22.01",
            "eval_cost": "2.00",
            "prefix_cost": "24.01",
            "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": [
            "cscart.gpf.group_id"
          ],
          "rows_examined_per_scan": 3,
          "rows_produced_per_join": 30,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "30.00",
            "eval_cost": "6.00",
            "prefix_cost": "60.01",
            "data_read_per_join": "480"
          },
          "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": [
            "cscart.gpf.feature_id",
            "cscart.gp.product_id",
            "const"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 30,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "30.00",
            "eval_cost": "6.00",
            "prefix_cost": "96.01",
            "data_read_per_join": "23K"
          },
          "used_columns": [
            "feature_id",
            "product_id",
            "variant_id",
            "lang_code"
          ]
        }
      }
    ]
  }
}

Result

feature_id product_id variant_id group_id
549 613 1311 39
549 614 1281 39
549 615 1312 39
549 616 1226 39
549 617 1311 40
549 618 1281 40
549 619 1312 40
549 620 1226 40
549 632 1226 44
549 633 1305 44
549 636 1226 46
549 637 1305 46
549 969 1226 119
549 970 1224 119
549 972 1226 120
549 973 1299 120
549 974 1310 120
549 975 1223 120
549 1013 1226 128
549 1014 1223 128
549 1016 1226 129
549 1017 1224 129
549 621 1311 132
549 1029 1292 132
549 622 1311 133
549 1030 1199 133