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 (
    2214, 5631, 33720, 4304, 5624, 5629, 
    6287, 6285, 1838, 276, 6283, 36492, 
    5625, 5620, 26978, 33719, 5618, 26975, 
    33715, 4823, 28163, 26976, 28164, 5627, 
    4814, 32703, 406, 4939, 26980, 32706, 
    3625, 26979
  ) 
  AND cscart_product_descriptions.lang_code = 'vi'

Query time 0.00244

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 (2214,5631,33720,4304,5624,5629,6287,6285,1838,276,6283,36492,5625,5620,26978,33719,5618,26975,33715,4823,28163,26976,28164,5627,4814,32703,406,4939,26980,32706,3625,26979) and cscart_product_descriptions.lang_code = 'vi'"
        }
      }
    ]
  }
}