SELECT 
  cscart_product_descriptions.product_id, 
  cscart_product_descriptions.short_description, 
  IF(
    cscart_product_descriptions.short_description = '' 
    OR cscart_product_descriptions.short_description IS NULL, 
    cscart_product_descriptions.full_description, 
    ''
  ) AS full_description, 
  cscart_product_descriptions.meta_keywords, 
  cscart_product_descriptions.meta_description, 
  cscart_product_descriptions.search_words, 
  cscart_product_descriptions.promo_text, 
  cscart_product_descriptions.unit_name 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    51480, 51479, 51494, 51495, 132, 112, 
    3, 78, 2, 77, 87, 66, 22421, 22424, 22290, 
    50981, 50982, 133, 45, 143, 50983, 51416, 
    51043, 51421, 51471, 51413, 51057, 
    51472, 51547, 51470, 51500, 51412
  ) 
  AND cscart_product_descriptions.lang_code = 'ru'

Query time 0.00094

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "22.41"
    },
    "table": {
      "table_name": "cscart_product_descriptions",
      "access_type": "range",
      "possible_keys": [
        "PRIMARY",
        "product_id"
      ],
      "key": "PRIMARY",
      "used_key_parts": [
        "product_id",
        "lang_code"
      ],
      "key_length": "9",
      "rows_examined_per_scan": 32,
      "rows_produced_per_join": 32,
      "filtered": "100.00",
      "index_condition": "((`test_uchur_k`.`cscart_product_descriptions`.`product_id` in (51480,51479,51494,51495,132,112,3,78,2,77,87,66,22421,22424,22290,50981,50982,133,45,143,50983,51416,51043,51421,51471,51413,51057,51472,51547,51470,51500,51412)) and (`test_uchur_k`.`cscart_product_descriptions`.`lang_code` = 'ru'))",
      "cost_info": {
        "read_cost": "19.21",
        "eval_cost": "3.20",
        "prefix_cost": "22.41",
        "data_read_per_join": "146K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description",
        "meta_keywords",
        "meta_description",
        "search_words",
        "promo_text",
        "unit_name"
      ]
    }
  }
}