framework/caching/ArrayCache.php
public function exists($key)
    {
        $key = $this->buildKey($key);
        return isset($this->_cache[$key]) && ($this->_cache[$key][1] === 0 || $this->_cache[$key][1] > microtime(true));
    }
public function exists($key)
    {
        $key = $this->buildKey($key);
        return isset($this->_cache[$key]) && ($this->_cache[$key][1] === 0 || $this->_cache[$key][1] > microtime(true));
    }
{@inheritdoc}