Source: http://www.sqlusa.com/bestpractices2005/executioninms/
DECLARE @StartTime datetime
DBCC DROPCLEANBUFFERS -- Force data/index pages out of buffer cache for valid test
SET @StartTime = GETDATE()
-- Measurement Starts
select * FROM doksprzed WHERE dok_idm = 'FIA -2006/00001'
-- Measurement Ends
SELECT ExecutionTimeInMS = DATEDIFF(millisecond, @StartTime, getdate())
GO