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 (
    100442, 100443, 100444, 100445, 100446, 
    100447, 100448, 100449, 100450, 100451, 
    100452, 100453, 100454, 100455, 100456, 
    100457, 100458, 100459, 100460, 100461, 
    100462, 100463, 100464, 100465, 100466, 
    100467, 100468, 100469, 100470, 100471, 
    100472, 100473, 100474, 100475, 100476, 
    100923, 100924, 100925, 100926, 100927, 
    100928, 100929, 100930, 100931, 100932, 
    100933, 100934, 100935
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00086

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 (100442,100443,100444,100445,100446,100447,100448,100449,100450,100451,100452,100453,100454,100455,100456,100457,100458,100459,100460,100461,100462,100463,100464,100465,100466,100467,100468,100469,100470,100471,100472,100473,100474,100475,100476,100923,100924,100925,100926,100927,100928,100929,100930,100931,100932,100933,100934,100935)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}