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 (
    255937, 261905, 285197, 295199, 308276, 
    175507, 183486, 210887, 219447, 230988, 
    238401, 258620, 291797, 295645, 308206, 
    308208, 308216, 308235, 308270, 308296, 
    311250, 321986, 31811, 68070
  ) 
  AND cscart_product_descriptions.lang_code = 'ru'

Query time 0.00094

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 (255937,261905,285197,295199,308276,175507,183486,210887,219447,230988,238401,258620,291797,295645,308206,308208,308216,308235,308270,308296,311250,321986,31811,68070)) and (`unicomps`.`cscart_product_descriptions`.`lang_code` = 'ru'))"
    }
  }
}