Yes, there are some openings for 10th graders at most schools. Certainly not as many as for 9th, definitely more than the openings available for 11th.
Not having a greencard or US citizenship is not an issue. After you are accepted at an accredited school, you need to apply for a student visa. A bigger issue is $. If your family can afford the tuition, great. (There is very little financial aid available for foreign nationals. Well, pretty much none.)
I guess the higher TOEFL and SSAT the better, but scores alone won’t get you in. Even scores and grades alone are not enough. There has to be something else in your application beyond grades and high test scores. You don’t participate in sports, play an instrument, or other extracurriculars, so what do you do when you aren’t studying? Do you have a hobby? Do you do volunteer work? You have to at least come up with something that makes you sound interesting and capable of contributing to the school community.
Also, think about what kind of school would match you best - size, formality, teaching philosophy, sports, etc. For example, if you’re completely disinterested in sports, a very sporty school would probably be a bad fit. Many schools require that you participate in a sport every season (fall, winter, spring), but there are some that allow you to substitute other activities.
Finally, think beyond the top 30 - “widen your net”.