API Query with multiple conditions

I can successfully make an API with a single query argument. For example:

/api/0/projects/myOrganization/myProject/issues/?query=timestamp<2019-10-01T00:00:00

or
/api/0/projects/myOrganization/myProject/issues/?query=environment:Production

But I would like to append both conditions at the same time. For example:

/api/0/projects/myOrganization/myProject/issues/?query=timestamp<2019-10-01T00:00:00&environment:Production

Unfortunately this doesn’t work. I have tried numerous ways. What am I missing?