Sandbox

SELECT 
  cscart_ult_product_descriptions.product_id, 
  cscart_ult_product_descriptions.short_description, 
  IF(
    cscart_ult_product_descriptions.short_description = "", 
    cscart_ult_product_descriptions.full_description, 
    ""
  ) AS full_description, 
  cscart_ult_product_descriptions.meta_keywords, 
  cscart_ult_product_descriptions.meta_description, 
  cscart_ult_product_descriptions.search_words, 
  cscart_ult_product_descriptions.promo_text 
FROM 
  cscart_ult_product_descriptions 
WHERE 
  cscart_ult_product_descriptions.product_id IN (
    51515, 51466, 51485, 51502, 51528, 51508, 
    51550, 51465, 51543, 51504, 51046, 
    51518, 51527, 51524, 51542, 51512
  ) 
  AND cscart_ult_product_descriptions.company_id = 1 
  AND cscart_ult_product_descriptions.lang_code = 'ru'

Query time 0.00036

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}