INSERT INTO daily_events
  (created_on, last_event_id, last_event_created_at)
VALUES
  ('2010-01-19', 23, '2010-01-19 10:23:11')
ON DUPLICATE KEY UPDATE
  last_event_id = IF(last_event_created_at < VALUES(last_event_created_at), VALUES(last_event_id), last_event_id),
  last_event_created_at = IF(last_event_created_at < VALUES(last_event_created_at), VALUES(last_event_created_at), last_event_created_at);

Source: https://thewebfellas.com/blog/conditional-duplicate-key-updates-with-mysql/