MySQL SELECT query hangs - Opening Tables INNODB
Yes, WordPress uses the default storage engine (which is InnoDB since MySQL 5.5).

I'm not sure I understand the problem. Can you execute the SELECT using the mysql command client? If you can, the problem is in the GUIs you use.

If you cannot (which means that you will receive an error, I think) you should investigate the error log. The only possible problem I can think now is a damaged table (REPAIR TABLE should solve the problem), but the error log should give you the exact answer.