How do i set the reset password to expire for 30 mins. I tried setting it on User Option for 1 hour waited for 2 hours and it did not expire and still let me use the authentication token in the link i received from email. Is there a code i need to change in com_users?
I've never seen such a setting in User Options.
As per official documentation on http://docs.joomla.org/Help34:Components_Users_Configuration , setting Time in Hours applies to Time period in hours for the Maximum Reset Count.
I am not aware of any other setting which manages expiration of Reset Password Token, and you certainly shouldn't touch any of core files, that being a biggest 'no-no thing' in Joomlaverse.