SELECT u.username, u.first_name, u.last_name, role.name AS role 

FROM keycloak_role role 

INNER JOIN realm ON role.realm = realm.id 

INNER JOIN user_role_mapping rm ON role.id = rm.role_id 

INNER JOIN user_entity u ON rm.user_id = u.id 

WHERE realm.name=:1 AND role.name = :2

It might be nice to do this in the web console though...