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 (
    350511, 355422, 350579, 355405, 350381, 
    350420, 350306, 354322, 350347, 354323, 
    350342, 350368, 355618, 350283, 355620, 
    354738, 350435, 355619, 350504, 355446, 
    350226, 350335, 350442, 350448, 350468, 
    355421, 354526, 350345, 350456, 356842, 
    350385, 350513, 355389, 350282, 350519, 
    355408, 355412, 350417, 358345, 353702, 
    350337, 350412, 358351, 350362, 355406, 
    350462, 353716, 350583, 354523, 350375, 
    358343, 350352, 353726, 350361, 353701, 
    350268, 350377, 350410, 350411, 354743, 
    355429, 355425, 350346, 355418, 358333, 
    350313, 350373, 353712, 353723, 355415, 
    355417, 355438, 354524, 350379, 350380, 
    350388, 355396, 355409, 355439, 355420, 
    350382, 350403, 354525, 358348, 358349, 
    350378, 355395, 353105, 353813, 350589, 
    355411, 358350, 350393, 350311, 355390, 
    358353, 358347, 350384, 350310, 350421
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00655

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "140.18"
    },
    "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": 100,
      "rows_produced_per_join": 100,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "120.18",
        "eval_cost": "20.00",
        "prefix_cost": "140.18",
        "data_read_per_join": "682K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`webmarco`.`cscart_product_descriptions`.`product_id` in (350511,355422,350579,355405,350381,350420,350306,354322,350347,354323,350342,350368,355618,350283,355620,354738,350435,355619,350504,355446,350226,350335,350442,350448,350468,355421,354526,350345,350456,356842,350385,350513,355389,350282,350519,355408,355412,350417,358345,353702,350337,350412,358351,350362,355406,350462,353716,350583,354523,350375,358343,350352,353726,350361,353701,350268,350377,350410,350411,354743,355429,355425,350346,355418,358333,350313,350373,353712,353723,355415,355417,355438,354524,350379,350380,350388,355396,355409,355439,355420,350382,350403,354525,358348,358349,350378,355395,353105,353813,350589,355411,358350,350393,350311,355390,358353,358347,350384,350310,350421)) and (`webmarco`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}