PHP Checking if array key exists and getting value

bechmark.php

<?php

$given = array_flip(range(1, 99999));


$start = microtime(true);
for ($i = 0; $i < 100000; $i++) {
    if (false !== isset($given['3434'])) {
        $value = $given['3434'];
    }
}
echo "First: " . (microtime(true) - $start) . PHP_EOL;

$start = microtime(true);
for ($i = 0; $i < 10000; $i++) {
    $value = $given['8912'] ?? null;
    if (null !== $value) {
        
    }
}
echo "Second: " . (microtime(true) - $start) . PHP_EOL;

results.txt

First: 0.02646803855896
Second: 0.0024199485778809

First:  $i < 100000;  // 1e5
Second:  $i < 10000;  // 1e4