KCET is exclusive for Karnataka candidates and you must have studied seven years there inclusive of 10+2 which you have not. Second, the subjects in the entrance test are Maths, Physcis and Chemistry so attempting the exam may be a problem if you are planning to appear for engineering.

If this query is for medical courses, admissions are through NEET. Please check the eligibility given on their website. It is very clear and ask for study in Karnataka irrespective of Karnataka Board or CBSE or even ICSE.