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 (
    43825, 6092, 35731, 23261, 40382, 47656, 
    3021, 47600, 6093, 48998, 2292, 1895, 
    47657, 47654, 47601, 47984, 455, 35249, 
    1412, 40761, 41170, 3471, 462, 47660, 
    4367, 1892, 5455, 1781, 1755, 1754, 
    2280, 3620
  ) 
  AND cscart_product_descriptions.lang_code = 'vi'

Query time 0.00656

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 (43825,6092,35731,23261,40382,47656,3021,47600,6093,48998,2292,1895,47657,47654,47601,47984,455,35249,1412,40761,41170,3471,462,47660,4367,1892,5455,1781,1755,1754,2280,3620) and cscart_product_descriptions.lang_code = 'vi'"
        }
      }
    ]
  }
}