How to decode a string in base64 with php

Hello i'm trying to decrypt a base64 string with php and i can't figure it out.

I am able to decrypt it with JavaScript using CryptoJS with the code below

var data = 'encrypted_url';
var key = "my_token";

function decryptByDES(cipherTextString, keyString) {
  var keyHex = CryptoJS.enc.Utf8.parse(keyString);

  var decrypted = CryptoJS.DES.decrypt({
    ciphertext: CryptoJS.enc.Base64.parse(cipherTextString)
  }, keyHex, {
    mode: CryptoJS.mode.ECB,
    padding: CryptoJS.pad.Pkcs7
  });
  return decrypted.toString(CryptoJS.enc.Utf8);
}

console.log(decryptByDES(data, key);

What is the equivalent of this code in PHP?

To decode and decode from base64 a string can use base64_encode() :

<?php
$str = 'This is an encoded string';
echo base64_encode($str);
?>

and now to decode:

<?php
$str = 'VGhpcyBpcyBhbiBlbmNvZGVkIHN0cmluZw==';
echo base64_decode($str);
?>

Now can apply this with any function.

Now this function could do the same using php 7.1:

<?php
$str = 'VGhpcyBpcyBhbiBlbmNvZGVkIHN0cmluZw==';
$key = '12345678';


function decryptByDES($str, $key) {
    $str = base64_decode($str);
    $key = base64_decode($key);
    $str = mcrypt_decrypt(MCRYPT_DES, $key, $str, MCRYPT_MODE_ECB);
    $str = str_replace("\x0", '', $str);
    return $str;
}

?>