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 (
    46714, 46196, 48032, 46195, 47367, 48033, 
    48030, 48037, 47365, 47363, 48031, 
    48034, 48036, 47366, 48035, 47357, 
    47358, 47360, 47359, 47364, 47361, 
    47362
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00822

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": 22,
          "filtered": 100,
          "index_condition": "cscart_product_descriptions.product_id in (46714,46196,48032,46195,47367,48033,48030,48037,47365,47363,48031,48034,48036,47366,48035,47357,47358,47360,47359,47364,47361,47362) and cscart_product_descriptions.lang_code = 'en'"
        }
      }
    ]
  }
}