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 (
    90266, 90273, 91311, 91313, 91315, 90267, 
    90274, 85649, 85650, 85651, 91312, 
    91314, 91316, 90263, 90270, 90269, 
    90275, 90265, 93356, 93357, 93358, 
    94081, 94082, 94085, 94088, 94089, 
    94090, 94093, 94095, 94096, 94097, 
    94098, 94099, 94116, 94117, 94118, 
    94165, 94166, 94167, 94168, 94169, 
    94170, 94171, 94172, 94173, 94174, 
    94175, 94176
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00103

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "21.63"
    },
    "table": {
      "table_name": "cscart_product_descriptions",
      "access_type": "range",
      "possible_keys": [
        "PRIMARY",
        "product_id"
      ],
      "key": "PRIMARY",
      "used_key_parts": [
        "product_id",
        "lang_code"
      ],
      "key_length": "9",
      "rows_examined_per_scan": 48,
      "rows_produced_per_join": 48,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "16.83",
        "eval_cost": "4.80",
        "prefix_cost": "21.63",
        "data_read_per_join": "183K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`nuie_scalesta_net`.`cscart_product_descriptions`.`product_id` in (90266,90273,91311,91313,91315,90267,90274,85649,85650,85651,91312,91314,91316,90263,90270,90269,90275,90265,93356,93357,93358,94081,94082,94085,94088,94089,94090,94093,94095,94096,94097,94098,94099,94116,94117,94118,94165,94166,94167,94168,94169,94170,94171,94172,94173,94174,94175,94176)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}