$host = '127.0.0.1';
$db   = 'cns';
$user = 'root';
$pass = 'password';
$charset = 'utf8mb4';

$dsn = "mysql:host=$host;dbname=$db;charset=$charset";
$options = [
    PDO::ATTR_ERRMODE            => PDO::ERRMODE_EXCEPTION,
    PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
    PDO::ATTR_EMULATE_PREPARES   => false,
];
try {
     $pdo = new PDO($dsn, $user, $pass, $options);

     $start = microtime(true);
     for ($t = 1; $t <= 150; $t++) {
   echo $t.PHP_EOL;
      $stmt = $pdo->query('select * from history_datas where coins_id = '.$t.' order by created_at desc');
  while ($row = $stmt->fetch())
  {
      //echo "\t".$row['coins_id'].'-'.$row['created_at'] . "\n";
  }
 }
 echo (microtime(true) - $start).PHP_EOL;
} catch (\PDOException $e) {
     throw new \PDOException($e->getMessage(), (int)$e->getCode());
}