将数据库中的本地时间存储为UTC时间（H：i：s），而不是使用当前时间（H：i：s）查询数据

I am developing a global application with twilio. in that application users store there start_hour and end_hours for there working time with there timezone. when a call comes we query all database and find those buyer who are available in that time. Application timezone is UTC. We need only hours to store and query on hours so we do not need time stamp. The problem is that when we convert user local time to UTC it gets changed Like if buyer choose

with Time zone (Africa/Addis_Ababa)

   Local Time                   UTC time
_____________________     _____________________
Start Hour | End Hour  => Start Hour | End Hour
1:00:00    | 23:00:00  => 22:00:00   | 20:00:00

my query formate in laravel is as

    $this->hours
    ->where('start_time','<=',$currentHour) // Hour 
    ->where('end_time','>',$currentHour)    // Filter

How can I Achieve this any