Rank Permission

public function createRank()
     {
         /*
This function has been intentionally created to be slow, inefficient and insecure. Your task is to improve the speed of executing this function and to correct it!
         We have a class called "Permissions" that contains the rights of what a user can do within a company. When creating a rank, we need to make sure that the permissions are validated correctly.

         Let's say that there are over 10000 permissions, each and every one of them has their own unique id.
         We need to validate that the user input is correct. We should check the following:
          - Can a user add this permission to a rank? Does every permission exist in the database?
          - Is the user attempting to add the same permission multiple times to the rank?
          - Does this rank already exist?
*/

         //A user wants to add a rank with the following permission id's
         $user_input_permissions = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10, 10];
         $user_input_rank_name = "Customer Support";
         $canAddRank = true;

        //loop through every permission and check if it exists
        foreach ($user_input_permissions as $permissionId)
        {
            $permission = Permission::where('id', $permissionId)->first();
            if(empty($permission))
            {
                $canAddRank = false;
                break;
            }
        }

        if(!$canAddRank)
            return "Couldn't add rank. User tried to add a rank that didn't exist!";

        $rank = new CompanyRank;
        $rank->title = $user_input_rank_name;
        $rank->permissions = $user_input_permissions;
        $rank->save();
        return "Added Rank Successfully!";
     }