Time of search in data base

Hi!!!! 
I created a data base under oracle9i and I want to measure the search
time in this data base. Let us suppose that I have this request to
carry out:

select * from usager where name = 'John' and age = 45;

I want to know time that oracle puts to make this search in the data
base. What's the script enabling me to determine this search time?

Thanks.