SELECT 
  pfv.variant_id, 
  pfv.position, 
  pfvd.variant 
FROM 
  cscart_product_feature_variants AS pfv 
  INNER JOIN cscart_product_feature_variant_descriptions AS pfvd ON pfv.variant_id = pfvd.variant_id 
  AND pfvd.lang_code = 'ru' 
WHERE 
  pfv.variant_id IN (
    1224, 1305, 1223, 1311, 1226, 1282, 1284, 
    1289, 1288, 1287, 1286, 1285, 1290, 
    1293, 1292, 1304, 1303, 1299, 1198, 
    1312
  )

Query time 0.00050

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "72.01"
    },
    "nested_loop": [
      {
        "table": {
          "table_name": "pfv",
          "access_type": "range",
          "possible_keys": [
            "PRIMARY"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "variant_id"
          ],
          "key_length": "3",
          "rows_examined_per_scan": 20,
          "rows_produced_per_join": 20,
          "filtered": "100.00",
          "index_condition": "(`cscart`.`pfv`.`variant_id` in (1224,1305,1223,1311,1226,1282,1284,1289,1288,1287,1286,1285,1290,1293,1292,1304,1303,1299,1198,1312))",
          "cost_info": {
            "read_cost": "44.01",
            "eval_cost": "4.00",
            "prefix_cost": "48.01",
            "data_read_per_join": "22K"
          },
          "used_columns": [
            "variant_id",
            "position"
          ]
        }
      },
      {
        "table": {
          "table_name": "pfvd",
          "access_type": "eq_ref",
          "possible_keys": [
            "PRIMARY"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "variant_id",
            "lang_code"
          ],
          "key_length": "9",
          "ref": [
            "cscart.pfv.variant_id",
            "const"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 20,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "20.00",
            "eval_cost": "4.00",
            "prefix_cost": "72.01",
            "data_read_per_join": "62K"
          },
          "used_columns": [
            "variant_id",
            "variant",
            "lang_code"
          ]
        }
      }
    ]
  }
}