Is it possible to specify rule processing order in Amazon Route 53?

Reply from the AWS support (emphasize mine):

If you setup a wildcard DNS entry for your Domain this will catch all queries where you haven`t specified a record.

As example:

localhost.domain.com. A 127.0.0.1
*.domain.com.         A 127.0.0.2
www.test.domain.com.  A 127.0.0.3

A query for localhost.domain.com. will return the specified A Record 127.0.0.1
A query for test.domain.com. will return the wildcard record 127.0.0.2
A query for www.test.domain.com. will return the specified record 127.0.0.3

This means a specified Record within your hosted Zone will always have a higher priority as a wildcard record.