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 (
    2672, 6121, 26926, 6164, 6116, 26963, 
    47899, 1473, 6133, 26923, 37702, 5811, 
    26858, 26848, 6171, 46552, 41564, 26862, 
    6614, 5810, 28377, 3705, 26863, 41562, 
    6134, 26921, 6123, 6127, 37700, 6170, 
    6541, 2683
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.02750

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 (2672,6121,26926,6164,6116,26963,47899,1473,6133,26923,37702,5811,26858,26848,6171,46552,41564,26862,6614,5810,28377,3705,26863,41562,6134,26921,6123,6127,37700,6170,6541,2683) and cscart_product_descriptions.lang_code = 'en'"
        }
      }
    ]
  }
}