poor query plan: ideal index from ORDER BY field is not used when extra columns retrieved - mrr=on and join_cache_level>2

| customers | CREATE TABLE `customers` (

  `customers_id` int(11) NOT NULL AUTO_INCREMENT,

  `customers_username` varchar(60) NOT NULL DEFAULT '',

  PRIMARY KEY (`customers_id`)

) ENGINE=InnoDB AUTO_INCREMENT=50001 DEFAULT CHARSET=latin1 |

| customers_info | CREATE TABLE `customers_info` (

  `customers_id` bigint(20) unsigned NOT NULL DEFAULT '0',

  `account_created_date` datetime DEFAULT NULL,

  PRIMARY KEY (`customers_id`),

  KEY `account_created_date_migrated_status` (`account_created_date`)

) ENGINE=InnoDB DEFAULT CHARSET=latin1 |

insert into customers (customers_id) select * from  seq_1_to_50000;

insert into customers_info select customers_id,NOW() - INTERVAL  customers_id DAY from customers;  

explain select customers.customers_id, customers_info.account_created_date from customers JOIN customers_info USING(customers_id) ORDER BY account_created_date DESC LIMIT 1;

+------+-------------+----------------+--------+---------------+--------------------------------------+---------+----------------------------------+------+--------------------------+

| id   | select_type | table          | type   | possible_keys | key                                  | key_len | ref                              | rows | Extra                    |

+------+-------------+----------------+--------+---------------+--------------------------------------+---------+----------------------------------+------+--------------------------+

|    1 | SIMPLE      | customers_info | index  | PRIMARY       | account_created_date_migrated_status | 9       | NULL                             |    1 | Using index              |

|    1 | SIMPLE      | customers      | eq_ref | PRIMARY       | PRIMARY                              | 4       | test.customers_info.customers_id |    1 | Using where; Using index |

+------+-------------+----------------+--------+---------------+--------------------------------------+---------+----------------------------------+------+--------------------------+

2 rows in set (0.02 sec)

MariaDB [test]> explain select customers.customers_id, customers.customers_username, customers_info.account_created_date from customers JOIN customers_info USING(customers_id) ORDER BY account_created_date DESC LIMIT 1

    -> ;

+------+-------------+----------------+--------+---------------+--------------------------------------+---------+----------------------------------+-------+--------------------------------------------------------------------+

| id   | select_type | table          | type   | possible_keys | key                                  | key_len | ref                              | rows  | Extra                                                              |

+------+-------------+----------------+--------+---------------+--------------------------------------+---------+----------------------------------+-------+--------------------------------------------------------------------+

|    1 | SIMPLE      | customers_info | index  | PRIMARY       | account_created_date_migrated_status | 9       | NULL                             | 50386 | Using index; Using temporary; Using filesort                       |

|    1 | SIMPLE      | customers      | eq_ref | PRIMARY       | PRIMARY                              | 4       | test.customers_info.customers_id |     1 | Using where; Using join buffer (flat, BKAH join); Key-ordered scan |