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 (
    13943, 14023, 13917, 13889, 13926, 13905, 
    13906, 13941, 13936, 14008, 14028, 
    13885, 13904, 14005, 13998, 13933, 
    13884, 13912, 14001, 13892, 13891, 
    13890, 13893, 14027
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00038

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost": 0.04252208,
    "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"],
          "loops": 1,
          "rows": 24,
          "cost": 0.04252208,
          "filtered": 100,
          "attached_condition": "cscart_product_descriptions.product_id in (13943,14023,13917,13889,13926,13905,13906,13941,13936,14008,14028,13885,13904,14005,13998,13933,13884,13912,14001,13892,13891,13890,13893,14027) and cscart_product_descriptions.lang_code = 'en'"
        }
      }
    ]
  }
}