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 (
    86644, 86711, 86713, 82632, 83529, 84543, 
    84544, 84609, 84610, 85126, 86183, 
    86206, 86507, 86783, 87294, 87295, 
    89078, 90003, 85103, 86131, 86154, 
    86639, 86708, 85850, 85851, 85860, 
    85861, 85089, 85175, 85221
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00080

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "16.06"
    },
    "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": 30,
      "rows_produced_per_join": 30,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "13.06",
        "eval_cost": "3.00",
        "prefix_cost": "16.06",
        "data_read_per_join": "114K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`nuie_scalesta_net`.`cscart_product_descriptions`.`product_id` in (86644,86711,86713,82632,83529,84543,84544,84609,84610,85126,86183,86206,86507,86783,87294,87295,89078,90003,85103,86131,86154,86639,86708,85850,85851,85860,85861,85089,85175,85221)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}