To get this information you need the statement's execution plan. Note execution, NOT explain!

This gives a breakdown of how long each specific step in the plan took. The easiest way is with the SQL monitor, which automatically captures long-running queries. This updates in real time, so you can see how a query progresses as it runs.

But you do need to be licensed for DIAG+TUNING for this!

And quick queries won't appear by default.

You can overcome both of these restrictions by tracing your session. This captures execution details of all SQL within it. If you want to trace an active session, find its sid and serial number and run:

exec DBMS_monitor.session_trace_enable ( <sid>, <serial#>, true, true );

And stop it again by calling:

exec DBMS_monitor.session_trace_disable ( <sid>, <serial#> );

You can then analyze the trace file using TKPROF or other tools.

You can read more about these techniques and more at:

https://blogs.oracle.com/sql/how-to-create-an-execution-plan