$endpoint = "https://www.whogohost.com/host/modules/addons/DomainsReseller/api/index.php";
$action = "/domains/example.com/nameservers";
$params = [
    "domain"    => "example.com",
];

$headers = [
    "username: email@example.com",
    "token: " . base64_encode(hash_hmac("sha256", "1234567890QWERTYUIOPASDFGHJKLZXCVBNM", "email@example.com:".gmdate("y-m-d H"))),
];

$curl = curl_init();

curl_setopt($curl, CURLOPT_URL, "{$endpoint}{$action}");
curl_setopt($curl, CURLOPT_POST, true);  // Note: This should be changed to curl_setopt($curl, CURLOPT_HTTPGET, true);
curl_setopt($curl, CURLOPT_POSTFIELDS, http_build_query($params));  // Note: This line is typically unnecessary for a GET request
curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, true);
curl_setopt($curl, CURLOPT_HTTPHEADER, $headers);

$response = curl_exec($curl);
curl_close($curl);