And therein lies your problem.
You haven't defined any FULLTEXT index, at all, so MySQL has no choice but to scan all rows.
CREATE TABLE photo (
tags mediumtext NOT NULL,
status enum('Successful','Processing','Failed') NOT NULL,
userid int NOT NULL,
FULLTEXT( title, tags )
) ENGINE = MyISAM;
MySQL won't enforce the referential integrity of the userid since this is a MyISAM table, but still putting an index on userid could well help the JOIN performance.