Can you what Apple ID is now associated with my MacBook Air using its serial number? My MacBook Air was stolen. Can you see what Apple ID is now associated with my MacBook Air using its serial number?
No, it is not possible to lookup that information for ordinary customers.

Apple has access to the information, but you cannot just call them and expect them to be able or willing to tell you. They would probably require an official request from the police with a warrant or similar.