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 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    1895, 1715, 5547, 43823, 21780, 5548, 
    5549, 46737, 34053, 1713, 5569, 46751, 
    5556, 16607, 46735, 5554, 1897, 858, 
    2113, 2136, 2132, 5551, 40452, 5553, 
    3471, 5567, 39613, 2133, 462, 40454, 
    2135, 40453
  ) 
  AND cscart_product_descriptions.lang_code = 'vi'

Query time 0.00548

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": "11",
          "used_key_parts": ["product_id", "lang_code"],
          "rows": 32,
          "filtered": 100,
          "index_condition": "cscart_product_descriptions.product_id in (1895,1715,5547,43823,21780,5548,5549,46737,34053,1713,5569,46751,5556,16607,46735,5554,1897,858,2113,2136,2132,5551,40452,5553,3471,5567,39613,2133,462,40454,2135,40453) and cscart_product_descriptions.lang_code = 'vi'"
        }
      }
    ]
  }
}