Can you work it out from this:
SELECT
d.Today,
StartTime = DATEADD(hour,8,d.Today),
EndTime = DATEADD(hour,10,d.Today)
FROM (SELECT Today = CAST(CAST(GETDATE() AS DATE) AS DATETIME)) d
For fast, accurate and documented assistance in answering your questions, please read this article.
Understanding and using APPLY, (I) and (II) Paul White
Hidden RBAR: Triangular Joins / The "Numbers" or "Tally" Table: What it is and how it replaces a loop Jeff Moden