I think you have confused the Content-Key order in Ticket::StateAfterPending under Ticket -> Core::Ticket.
Key should be pending auto close+ and the content should be closed successful
Also Ticket::PendingAutoStateType should be pending auto. The state for which the subsequent status should be set automatically, must be of type pending auto.
OTRS is trying to find the state that should be set after pending time for 'closed successful' has been reached and obviously cannot. What you want to tell OTRS is 'when the pending time for state xy (in this case I assume pending auto close +) is reached, set state equal to closed successful'.
OTRS 3.3.x (private/testing) on Windows Server 2008 with MSSQL database.
OTRS 3.3.x (private/testing) on CentOS with MySQL database and apache
Can you test using a value other than 'closed successful' in the field content to see whether it still gives an error.
You can also try to delete the entry (pending auto+ as key and closed successful as content) and test with only pending auto close- as key and closed unsuccessful as content and report the result.
OTRS 3.3.x (private/testing) on Windows Server 2008 with MSSQL database.
OTRS 3.3.x (private/testing) on CentOS with MySQL database and apache