Setting custom timezone for config.active_record.default_timezone

I’m using a Rails application to access a database from a legacy
application. This application stores all datetime fields using
Europe/Madrid timezone.

From what I’ve seem, it’s only possible to set
config.active_record.default_timezone to :utc (default) or :local which
uses the OS timezone.

Since I cannot guarantee that my OS timezone will always be
I would like to set a specific timezone for active record.

Is there another of doing this?