$q = $modx->newQuery('modUser');
$s = $q->prepare();
$s->execute();

print_r($s->fetch(2));

Array
(
    [modUser_id] => 2
    [modUser_username] => xxxx
    [modUser_password] => xxxxxx
    [modUser_cachepwd] => 
    [modUser_class_key] => modUser
    [modUser_active] => 1
    [modUser_remote_key] => 
    [modUser_remote_data] => 
    [modUser_hash_class] => hashing.modPBKDF2
    [modUser_salt] => 
    [modUser_primary_group] => 22
    [modUser_session_stale] => 
    [modUser_sudo] => 1
)

$q = $modx->newQuery('modUser');
$q->select(array(
    "{$q->getAlias()}.*",
));
$s = $q->prepare();
$s->execute();

print_r($s->fetch(2));

Array
(
    [id] => 2
    [username] => xxxxxx
    [password] => xxxxxxx
    [cachepwd] => 
    [class_key] => modUser
    [active] => 1
    [remote_key] => 
    [remote_data] => 
    [hash_class] => hashing.modPBKDF2
    [salt] => 
    [primary_group] => 22
    [session_stale] => 
    [sudo] => 1
)