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 (
    5589, 5447, 4365, 31886, 5469, 4468, 
    4358, 5464, 5474, 5962, 4464, 4364, 
    4466, 31897, 47280, 4359, 5481, 5459, 
    31896, 48032, 4357, 48322, 31892, 31890, 
    4467, 47088, 31898, 5483, 47090, 48033, 
    48030, 48037
  ) 
  AND cscart_product_descriptions.lang_code = 'vi'

Query time 0.00859

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 (5589,5447,4365,31886,5469,4468,4358,5464,5474,5962,4464,4364,4466,31897,47280,4359,5481,5459,31896,48032,4357,48322,31892,31890,4467,47088,31898,5483,47090,48033,48030,48037) and cscart_product_descriptions.lang_code = 'vi'"
        }
      }
    ]
  }
}