How to stop time subtraction on 00:00:00 in laravel

I am using query which is subtracting time. Problem is when it reaches to 00:00:00 it doesn't stop subtracting and it start going in negative like " - 00:20:00"

Sale::where('date','=',$current->toDateString())->where('time','<=',$current->toTimeString()) ->update(['duration' => DB::raw('DATE_SUB(duration, INTERVAL 1 MINUTE)')]);

I want to stop it on 00:00:00

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