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, 
  cscart_product_descriptions.unit_name 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    426, 429, 428, 410, 450, 474, 473, 448, 
    493, 409, 456, 431, 466, 484, 470, 490, 
    451, 491, 411, 486, 471, 481, 489, 415, 
    430, 414, 475, 412, 417
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00061

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "69.61"
    },
    "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": 29,
      "rows_produced_per_join": 29,
      "filtered": "100.00",
      "index_condition": "((`danishecarter_latest`.`cscart_product_descriptions`.`product_id` in (426,429,428,410,450,474,473,448,493,409,456,431,466,484,470,490,451,491,411,486,471,481,489,415,430,414,475,412,417)) and (`danishecarter_latest`.`cscart_product_descriptions`.`lang_code` = 'en'))",
      "cost_info": {
        "read_cost": "63.81",
        "eval_cost": "5.80",
        "prefix_cost": "69.61",
        "data_read_per_join": "132K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description",
        "unit_name"
      ]
    }
  }
}