Filtering by entity key name in Google App Engine on Python

On Google App Engine to query the data store with Python, one can use GQL or Entity.all() and then filter it. So for example these are equivalent

gql = "SELECT * FROM User WHERE age >= 18"
db.GqlQuery(gql)

and

query = User.all()
query.filter("age >=", 18)

Now, it's also possible to query things by key name. I know that in GQL you do it like this

gql = "SELECT * FROM User WHERE __key__ >= Key('User', 'abc')"
db.GqlQuery(gql)

But how would you now use filter to do the same?

query = User.all()
query.filter("__key__ >=", ?????)