SELECT 
  pfv.feature_id, 
  pfv.product_id, 
  pfv.variant_id, 
  fv.position, 
  fvd.variant 
FROM 
  cscart_product_features_values AS pfv 
  INNER JOIN cscart_product_feature_variants AS fv ON pfv.feature_id = fv.feature_id 
  AND pfv.variant_id = fv.variant_id 
  INNER JOIN cscart_product_feature_variant_descriptions AS fvd ON pfv.variant_id = fvd.variant_id 
  AND fvd.lang_code = 'ru' 
WHERE 
  pfv.feature_id IN (193) 
  AND pfv.product_id IN (
    84, 109, 118, 19, 131, 146, 13, 61, 95, 
    15, 9, 85, 59, 111, 144, 60, 123, 145, 
    113, 6, 14, 63, 136, 50984, 127, 134, 
    42, 50985, 50986, 50988, 50993, 50992
  ) 
  AND pfv.lang_code = 'ru'

Query time 0.00166

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "19.31"
    },
    "nested_loop": [
      {
        "table": {
          "table_name": "pfv",
          "access_type": "range",
          "possible_keys": [
            "PRIMARY",
            "fl",
            "variant_id",
            "lang_code",
            "product_id",
            "fpl",
            "idx_product_feature_variant_id"
          ],
          "key": "idx_product_feature_variant_id",
          "used_key_parts": [
            "product_id",
            "feature_id",
            "lang_code"
          ],
          "key_length": "12",
          "rows_examined_per_scan": 33,
          "rows_produced_per_join": 33,
          "filtered": "100.00",
          "using_index": true,
          "cost_info": {
            "read_cost": "3.88",
            "eval_cost": "3.30",
            "prefix_cost": "7.18",
            "data_read_per_join": "25K"
          },
          "used_columns": [
            "feature_id",
            "product_id",
            "variant_id",
            "lang_code"
          ],
          "attached_condition": "((`test_uchur_k`.`pfv`.`feature_id` = 193) and (`test_uchur_k`.`pfv`.`product_id` in (84,109,118,19,131,146,13,61,95,15,9,85,59,111,144,60,123,145,113,6,14,63,136,50984,127,134,42,50985,50986,50988,50993,50992)) and (`test_uchur_k`.`pfv`.`lang_code` = 'ru'))"
        }
      },
      {
        "table": {
          "table_name": "fv",
          "access_type": "eq_ref",
          "possible_keys": [
            "PRIMARY",
            "feature_id"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "variant_id"
          ],
          "key_length": "3",
          "ref": [
            "test_uchur_k.pfv.variant_id"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 1,
          "filtered": "5.00",
          "cost_info": {
            "read_cost": "8.25",
            "eval_cost": "0.17",
            "prefix_cost": "18.73",
            "data_read_per_join": "2K"
          },
          "used_columns": [
            "variant_id",
            "feature_id",
            "position"
          ],
          "attached_condition": "(`test_uchur_k`.`fv`.`feature_id` = 193)"
        }
      },
      {
        "table": {
          "table_name": "fvd",
          "access_type": "eq_ref",
          "possible_keys": [
            "PRIMARY"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "variant_id",
            "lang_code"
          ],
          "key_length": "9",
          "ref": [
            "test_uchur_k.pfv.variant_id",
            "const"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 1,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "0.41",
            "eval_cost": "0.17",
            "prefix_cost": "19.31",
            "data_read_per_join": "5K"
          },
          "used_columns": [
            "variant_id",
            "variant",
            "lang_code"
          ]
        }
      }
    ]
  }
}