If they increase price for same policy for a 30yr old male then you have to pay more. It may happen at 31 or /and 39 or any other year or never.
Insurance companies change price as per their claim experience and inflation.
Health insurance works differently than term insurance.
Health insurance premium is different for different ages, your premium for age 30 will be different then age 35. Also anyone entering at age 35 will pay same premium as the one who is a subscriber since long.
Premium lock means you'll continue to pay latest premium applicable to your entry age as long as you don't make a claim.