Use OUTER APPLY instead of LEFT JOIN:
SELECT u.id, mbg.marker_value
FROM dps_user u
OUTER APPLY
(SELECT TOP 1 m.marker_value, um.profile_id
FROM dps_usr_markers um (NOLOCK)
INNER JOIN dps_markers m (NOLOCK)
ON m.marker_id= um.marker_id AND
m.marker_key = 'moneyBackGuaranteeLength'
WHERE um.profile_id=u.id
ORDER BY m.creation_date
) AS MBG
WHERE u.id = 'u162231993';
Unlike JOIN, APPLY allows you to reference the u.id inside the inner query.