Yes, if you have passed from an institution in kerala, you can happily apply for KCET.

This is the info available on Careers 360 regarding eligibility of KCET.

• Candidates must be citizens of India. 

Karnataka CET Eligibility Criteria 2018 related to Domicile

• Candidates must have studied and passed from a recognised institution situated in Karnataka. The academic study from a state institute should be for a minimum period of 7 years, starting from 1st standard to 2nd PUC/12th standard as on July 1 of the exam year.

• Candidates should have appeared/passed either SSLC/10th standard or 2nd PUC/12th standard exam from Karnataka.