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 (
    52, 47599, 41399, 4705, 1836, 45503, 
    4515, 47603, 31872, 23402, 5813, 23401, 
    1059, 4715, 22534, 4346, 1835, 5986, 
    34553, 48772, 19270, 2150, 1784, 4116, 
    41334, 6545, 3528, 1408, 29698, 31626, 
    1058, 19289
  ) 
  AND cscart_product_descriptions.lang_code = 'vi'

Query time 0.00574

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 (52,47599,41399,4705,1836,45503,4515,47603,31872,23402,5813,23401,1059,4715,22534,4346,1835,5986,34553,48772,19270,2150,1784,4116,41334,6545,3528,1408,29698,31626,1058,19289) and cscart_product_descriptions.lang_code = 'vi'"
        }
      }
    ]
  }
}