-- SOLVED --
Ok, I am baffled. Firstly, when I was doing my query from code I was doing a SELECT on `USERNAME` using only the username, not @domain.tld. So that's my first problem and why my query failed. However, it would appear that the data displayed in phpmyadmin (for column username) is encrypted while from the mysql cli the data is not. What gave me a clue was enabling SQL Debug in roundcubemail. So a simple sql query using the user@domain.tld is all that is needed in either phpmyadmin sql or mysql cli (or code). However, in phpmyadmin, the resulting username displayed is encrypted or obfuscated . So there would appear to be a setting (though not in the current /usr/share/phpmyadmin/config.inc.php config that would indicate encrypt/decrypt option, but perhaps in the phpmyadmin docs.
IP changed to 0.0.0.0 for post
Thanks for you help!!
mysql> select * from users;
+---------+-------------------+-------------+-------+---------------------+---------------------+----------+-------------+
| user_id | username | mail_host | alias | created | last_login | language | preferences |
+---------+-------------------+-------------+-------+---------------------+---------------------+----------+-------------+
| 1 | user@domain.tld | 0.0.0.0 | | 2012-06-30 06:54:01 | 2012-06-30 06:54:01 | en_US | NULL |
+---------+-------------------+-------------+-------+---------------------+---------------------+----------+-------------+
1 row in set (0.00 sec)
[30-Jun-2012 06:54:01 -0700]: query(1): SELECT * FROM users WHERE mail_host = 0.0.0.0 AND username = 'user@domain.tld;