session problem in Firefox

My project does online reservation. When user enters the site they tries search something for given location and date-time. Before the start of the searching in controller I do clear session after transferred some session data into the variables. Then I flush the session and then put that variables back to the session again. This works fine with chrome but won't work with Firefox & Safari.

Here is the my code:

$token = session('_token');
session()->flush();
session()->put('_token', $token);

When i look the session token after search operation in controller, token changes everytime for firefox, but it remains same in chrome. I don't know why this happens.