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 (
    27361, 47632, 1893, 47593, 47613, 38074, 
    6091, 40927, 6281, 3288, 49164, 33310, 
    47903, 28159, 43817, 47631, 35279, 
    47597, 1767, 17265, 47655, 47922, 47921, 
    47896, 47924, 47923, 33312, 3287, 3286, 
    3872, 5300, 5297
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.06262

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 (27361,47632,1893,47593,47613,38074,6091,40927,6281,3288,49164,33310,47903,28159,43817,47631,35279,47597,1767,17265,47655,47922,47921,47896,47924,47923,33312,3287,3286,3872,5300,5297) and cscart_product_descriptions.lang_code = 'en'"
        }
      }
    ]
  }
}