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 (
    10530, 10531, 10532, 10533, 10534, 10535, 
    10536, 10537, 10538, 10539, 10540, 
    10541, 10542, 10524, 10543, 10544, 
    10323, 10324, 10325, 10326
  ) 
  AND cscart_product_descriptions.lang_code = 'ru'

Query time 0.00059

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_product_descriptions",
      "access_type": "range",
      "possible_keys": ["PRIMARY", "product_id"],
      "key": "PRIMARY",
      "key_length": "9",
      "used_key_parts": ["product_id", "lang_code"],
      "rows": 20,
      "filtered": 100,
      "index_condition": "cscart_product_descriptions.product_id in (10530,10531,10532,10533,10534,10535,10536,10537,10538,10539,10540,10541,10542,10524,10543,10544,10323,10324,10325,10326) and cscart_product_descriptions.lang_code = 'ru'"
    }
  }
}

Result

product_id short_description full_description meta_keywords meta_description search_words promo_text unit_name
10323
10324
10325
10326
10524
10530
10531
10532
10533
10534
10535
10536
10537
10538
10539
10540
10541
10542
10543
10544