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 (
    2695, 36329, 319, 48769, 31630, 37304, 
    6059, 38143, 5837, 6060, 27357, 38152, 
    35249, 2932, 27358, 14822, 18201, 2461, 
    41441, 31909, 40824, 31908, 6099, 5779, 
    33177, 4004, 49306, 1897, 401, 3774, 
    27360, 6577
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.06065

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 (2695,36329,319,48769,31630,37304,6059,38143,5837,6060,27357,38152,35249,2932,27358,14822,18201,2461,41441,31909,40824,31908,6099,5779,33177,4004,49306,1897,401,3774,27360,6577) and cscart_product_descriptions.lang_code = 'en'"
        }
      }
    ]
  }
}