Q:

MySQL Query: Find column where key like "Y" then use another columns unique ID to update a third column with something?

I am going to try to do my best to explain the SQL query I'm trying to achieve
I have the following structure:
Table usermeta
Columns: : user_id, meta_key, meta_value
I need to find all meta_key where '_expired_user_expired" and meta_value is 'Y'
SELECT * 
FROM usermeta
WHERE meta_key LIKE '_expire_user_expired' AND meta_value LIKE 'y';

Now to the hard part (for me)
I need to use the unique value from column user_id to update meta_key 'user_disabled' to have meta_value '1'.
Visual explanation: 
╔══════════════╦════════════════════════╦══════════════════╗
║   user_id    ║    meta_key            ║     meta_value   ║
╠══════════════╩════════════════════════╩══════════════════╣
║      1       ║ user_disabled          ║         0        ║
║      1       ║ _expired_user_expired  ║         Y        ║
║      2       ║ user_disabled          ║         0        ║
║      2       ║ _expired_user_expired  ║         N        ║
║      3       ║ user_disabled          ║         0        ║
║      3       ║ _expired_user_expired  ║         N        ║
╠══════════════╩════════════════════════╩══════════════════╣

After a successful query would become:
╔══════════════╦════════════════════════╦══════════════════╗
║   user_id    ║    meta_key            ║     meta_value   ║
╠══════════════╩════════════════════════╩══════════════════╣
║      1       ║ user_disabled          ║         1        ║
║      1       ║ _expired_user_expired  ║         Y        ║
║      2       ║ user_disabled          ║         0        ║
║      2       ║ _expired_user_expired  ║         N        ║
║      3       ║ user_disabled          ║         0        ║
║      3       ║ _expired_user_expired  ║         N        ║
╠══════════════╩════════════════════════╩══════════════════╣

A:

You could use the update join syntax:
UPDATE usermeta a
JOIN   usermeta b ON a.user_id = b.user_id AND
                     a.meta_key = 'user_disabled' AND
                     b.meta_key = '_expired_user_expired' AND
                     b.meta_value = 'Y'
SET    a.meta_value = 1

