you could roughly find the time in v$session_longops if the query takes more than 6 seconds, I say roughly because if your query has several operations then you would have to sum them up in v$session_longops

other option is sql*plus set timing on and run the query

other option is sql_trace the session if you want to do it remotely

other option is use dbms_utility.GET_TIME, execute it before your query and store the result in a variable, then execute again at end of your query and substract the variable you would get the execution time (probably differs by some milliseconds)

may be there are more options but right now I can think of these 4 only