Try this instead:
COUNTD(IF [StarttimeAsDate]=[Today] AND [TerminatetimeAsDate]=[Today] THEN [Order ID] END)
Note: The reason we use [Order ID] in this is that COUNTD counts distinct values. If you return 1 or 0, then COUNTD will probably always return 1 or 2 as each value (1 and 0) will only be counted once. If we use [Order ID], it will count each distinct order once.
Thank you, Ken, it worked. Appreciate the detailed explanation!