PHP Secure Token Generator: Create and validate tokens stored in MySQL table

This class can generate and validate tokens stored in a database.

It can generate a unique token and store it in a database table using PDO.

The token values can be valid for a given expiry time that by default it is 60 seconds.

The class can also validate the token value by checking if it exists and is still valid by looking at the token expiry time.

The token may also be refreshed to extend its lifetime, or destroyed so it is no longer valid.