What's the fastest lap time ever in a race for Lewis Hamilton?
fastest lap time ever refers to min(fastestLapTime)
SELECT T2.fastestLapTime FROM drivers AS T1 INNER JOIN results AS T2 ON T2.driverId = T1.driverId WHERE T1.forename = 'Lewis' AND T1.surname = 'Hamilton' AND T2.fastestLapTime IS NOT NULL ORDER BY T2.fastestLapTime ASC LIMIT 1