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 (
    3583, 2455, 473, 46188, 32311, 40371, 
    652, 2296, 27854, 3661, 37825, 47172, 
    2585, 32368, 27935, 3637, 47276, 19278, 
    33362, 31962, 2453, 40916, 27367, 35480, 
    4341, 35488, 48683, 37321, 6445, 2583, 
    48677, 45574
  ) 
  AND cscart_product_descriptions.lang_code = 'vi'

Query time 0.00890

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 (3583,2455,473,46188,32311,40371,652,2296,27854,3661,37825,47172,2585,32368,27935,3637,47276,19278,33362,31962,2453,40916,27367,35480,4341,35488,48683,37321,6445,2583,48677,45574) and cscart_product_descriptions.lang_code = 'vi'"
        }
      }
    ]
  }
}