future date check

I have a small problem in my dates. For example, I encoded the following date:

date training : 10/09/2019 | hour_start : 08:00 | hour_end : 10:00 | motorbike : 000001

Then, I want to encode for on 11/09/2019 the same informations

My checking compares only the hours (start & end) and no the date.

So, for my example, I have a blocking...

My problem is in my code

$date_seance = $request->get('date_seance'); 
$hour_start = $request->get('hour_start'); 
$hour_end = $request->get('hour_end'); 
$fk_motorbike = $request->get('fk_motorbike');
$fk_student = $request->get('fk_student');
$fk_former = $request->get('fk_former');
$fk_typeseance = $request->get('fk_typeseance');


$conflictTraining = Training::where('fk_motorbike', $request->get('fk_motorbike')) 
->whereDate('date_seance', "=" , $date_seance)  
->where('hour_start', "<=" , $request->get('hour_start')) 
->where('hour_end', ">=" , $request->get('hour_end'))
->where('fk_former', $request->get('fk_former'))
->first();

 if(isset($conflictTraining)){
            return redirect()->route('trainings.index')
             ->with('error', 'The training is already booked');
        }

For information my hours are in format string is it a problem ?

 Schema::create('trainings', function (Blueprint $table) {
            $table->bigIncrements('id');
            $table->date('date_seance');
            $table->string('hour_start');
            $table->string('hour_end');

Thank you for your help.