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 (
    48557, 1267, 35177, 1977, 119, 2291, 
    27356, 35167, 35165, 35174, 35176, 
    35173, 35170, 35172, 35171, 6092, 40382, 
    118, 1982, 36272, 47656, 44423, 1585, 
    35168, 47824, 35166, 35169, 5992, 1535, 
    41429, 47600, 6093
  ) 
  AND cscart_product_descriptions.lang_code = 'vi'

Query time 0.00659

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 (48557,1267,35177,1977,119,2291,27356,35167,35165,35174,35176,35173,35170,35172,35171,6092,40382,118,1982,36272,47656,44423,1585,35168,47824,35166,35169,5992,1535,41429,47600,6093) and cscart_product_descriptions.lang_code = 'vi'"
        }
      }
    ]
  }
}