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.unit_name 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    14, 67, 37, 53, 52, 5, 8, 4, 1, 165, 166, 
    168, 167, 169, 86, 106, 105, 101, 33, 
    32, 49, 59, 58, 60, 42, 39, 40, 43, 56, 
    57, 55, 50
  ) 
  AND cscart_product_descriptions.lang_code = 'ru'

Query time 0.00801

JSON explain

{
  "query_block": {
    "select_id": 1,
    "nested_loop": [
      {
        "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": 32,
          "filtered": 100,
          "index_condition": "cscart_product_descriptions.product_id in (14,67,37,53,52,5,8,4,1,165,166,168,167,169,86,106,105,101,33,32,49,59,58,60,42,39,40,43,56,57,55,50) and cscart_product_descriptions.lang_code = 'ru'"
        }
      }
    ]
  }
}