In my spare time I usually go out with my friends.
This is grammatically correct. However, if you’re talking about something you do regularly or habitually then present simple tense is all you need:
- In my spare time I go out with my friends.
Only use usually when you want to make a contrast between something you do habitually, and something that you do, or have to do, because of exceptional or unforeseen circumstances:
- In my spare time I usually go out with my friends, but today I have my IELTS interview.