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 (
    238400, 238518, 258627, 279059, 322596, 
    10101, 141331, 182500, 183418, 210394, 
    216091, 216439, 244556, 285152, 304053, 
    311249, 326960, 154729, 163659, 183540, 
    200612, 255788, 255803, 274116
  ) 
  AND cscart_product_descriptions.lang_code = 'ru'

Query time 0.00082

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "10.82"
    },
    "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": 24,
      "rows_produced_per_join": 24,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "8.42",
        "eval_cost": "2.40",
        "prefix_cost": "10.82",
        "data_read_per_join": "109K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description",
        "meta_keywords",
        "meta_description",
        "search_words",
        "promo_text",
        "unit_name"
      ],
      "attached_condition": "((`unicomps`.`cscart_product_descriptions`.`product_id` in (238400,238518,258627,279059,322596,10101,141331,182500,183418,210394,216091,216439,244556,285152,304053,311249,326960,154729,163659,183540,200612,255788,255803,274116)) and (`unicomps`.`cscart_product_descriptions`.`lang_code` = 'ru'))"
    }
  }
}