$wall_get = json_decode(file_get_contents('https://api.vk.com/method/wall.get?owner_id=-1&count=50&filter=owner&access_token=TOKEN&v=5.101'), true);
foreach ($wall_get['response']['items'] as $result_wall_get) { echo $result_wall_get['id'];}
date = 1565458434
(дата написания вопроса, если что)if ($result_wall_get['date'] == '1565458434') {
echo $result_wall_get['id']
}