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 (
    30368, 47828, 1929, 28446, 1930, 22302, 
    32189, 32188, 28450, 32187, 32186, 
    32191, 47831, 47825, 47826, 47830, 
    47832, 47827, 47829
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.01704

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": 19,
          "filtered": 100,
          "index_condition": "cscart_product_descriptions.product_id in (30368,47828,1929,28446,1930,22302,32189,32188,28450,32187,32186,32191,47831,47825,47826,47830,47832,47827,47829) and cscart_product_descriptions.lang_code = 'en'"
        }
      }
    ]
  }
}