laravel slow query issue - php

Question

I want to optimize my query I am executing with Laravel. I'm using MySQL for my project and I have a table named locations. It has more than 2 million records.
When I execute the code below it's too slow. How can I optimize my query to improve the speed?
foreach ($employees as $employee){
$percentage = 0;
if ($employee->position->zones->count() > 0) {
if($employee->position->zones->first()->workingzones->count() > 0) {
$workingZone = $employee->position->zones->first()->workingzones->last();
$tagCode = $employee->rfids->first()->rfid_id;
$zoneTime = DB::table('location')
->select(DB::raw('count(*) as count'))
->where('tagCode', $tagCode)
->where('xLocation', '>', $workingZone->x1)
->where('xLocation', '<', $workingZone->x3)
->where('yLocation', '>', $workingZone->y3)
->where('yLocation', '<', $workingZone->y1)
->where('locationDate', '>=',''.$currentDate.' 00:00:01')
->where('locationDate', '<=', $currentDate. ' 23:59:59')
->get();
$totalWorkedTime = DB::table('location')
->select(DB::raw('count(*) as count'))
->where('tagCode', $tagCode)
->where('locationDate', '>=',''.$currentDate.' 00:00:01')
->where('locationDate', '<=', $currentDate. ' 23:59:59')->get();
if ($zoneTime->first()->count == 0 || $totalWorkedTime->first()->count == 0) {
$percentage = 0;
}else {
$percentage = (int)ceil(($zoneTime->first()->count /12 )* 100 / ($totalWorkedTime->first()->count / 12));
}
}
}
$employee->percentage = $percentage;
}

Answer 1

You do a full ->get() twice and only use the ->first() result. When you just need 1, just use ->first() instead of ->get().
Also you can eagerload the position and zones while fetching the employees , and saving 2 additional queries per loop (- grouped eagerload queries on total), like this:
$employees = Employee::where(/*where foo here*/)
->with('position.zones')
->get();
And to consume less mem, chunk it.
Employee::where(/*where foo here*/)
->with('position.zones')
->chunk(200, function ($employees) {
foreach ($employees as $employee) {
// current code here with ->first() instead of ->get()
}
});

Answer 2

Adding indexes on the following columns should improve your performance:
xLocation
yLocation
locationDate
How to add indexes with an MySQL query:
https://dev.mysql.com/doc/refman/5.7/en/create-index.html
or if you use Laravel's migrations: https://laravel.com/docs/5.4/migrations#indexes
Edit:
Also: instead of doing the COUNT(*) on both select queries, use COUNT(`id`), so you don't count all columns, but only the id column