CREATE TABLE #Users 
    (UserID VARCHAR(20) NOT NULL
    ,Created_DT DATETIME DEFAULT (GETDATE())
    ,Expiry_DT DATETIME DEFAULT (DATEADD(hour, 2, GETDATE()))
    ,Is_Expired AS CASE WHEN GETDATE() > Expiry_DT THEN 'Y' ELSE 'N' END)

INSERT INTO #Users (UserID)
SELECT 'Dwain'

SELECT * FROM #Users

-- When User validates
UPDATE #Users SET Expiry_DT = '9999-12-31' WHERE UserID = 'Dwain'
SELECT * FROM #Users

DROP TABLE #Users