gistfile1.txt

| message_delivery_results | CREATE TABLE `message_delivery_results` (
  `id` int(11) NOT NULL auto_increment,
  `job_id` int(11) default NULL,
  `message_id` int(11) default NULL,
  `contact_id` int(11) default NULL,
  `provider_response` int(11) default NULL,
  `attempted_at` datetime default NULL,
  `current_state` int(11) default NULL,
  `last_state_at` datetime default NULL,
  `delivered_at` datetime default NULL,
  `delivery_attempts` int(11) default '0',
  `created_at` datetime default NULL,
  `updated_at` datetime default NULL,
  `confirmed` tinyint(1) default NULL,
  `assistance_required` tinyint(1) default NULL,
  `response_time` int(11) default NULL,
  `can_respond` tinyint(1) default NULL,
  `status` int(10) default NULL,
  `provider_error_string` text,
  PRIMARY KEY  (`id`),
  KEY `index_message_delivery_results_on_attempted_at` (`attempted_at`),
  KEY `index_message_delivery_results_on_attempted_at_delivered_at` (`attempted_at`,`delivered_at`)
) ENGINE=InnoDB AUTO_INCREMENT=9747 DEFAULT CHARSET=latin1 | 


mysql> explain SELECT * FROM `message_delivery_results` WHERE (delivered_at IS NULL AND attempted_at < NOW() - INTERVAL 300 SECOND);
+----+-------------+--------------------------+------+------------------------------------------------------------------------------------------------------------+------+---------+------+------+-------------+
| id | select_type | table                    | type | possible_keys                                                                                              | key  | key_len | ref  | rows | Extra       |
+----+-------------+--------------------------+------+------------------------------------------------------------------------------------------------------------+------+---------+------+------+-------------+
|  1 | SIMPLE      | message_delivery_results | ALL  | index_message_delivery_results_on_attempted_at,index_message_delivery_results_on_attempted_at_delivered_at | NULL | NULL    | NULL | 9529 | Using where | 
+----+-------------+--------------------------+------+------------------------------------------------------------------------------------------------------------+------+---------+------+------+-------------+
1 row in set (0.00 sec)