how to use a SHA256 hash in Hex format in laravel

I am working on integrating with Hotelbeds API, but I have a problem with the authentication they require to send both the API Key and the X-Signature, a SHA256 hash in Hex format calculated from the API key, the secret plus current timestamps in seconds here is their example:

#!/bin/bash 
apiKey="yourApiKey"
secret="yourSecret"
curl -i \
-X GET \
-H 'Accept:application/json' \
-H 'Api-key:'$apiKey'' \
-H 'X-Signature:'$(echo -n ${apiKey}${secret}$(date +%s)|sha256sum|awk '{ print $1}')'' \
https://api.test.hotelbeds.com/hotel-api/1.0/status

and this one also

//Begin UTC creation
var utcDate = Math.floor(new Date().getTime() / 1000);

//Begin Signature Assembly
var publicKey = environment["Api-key"];
var privateKey = environment["secret"];

var assemble = (publicKey+privateKey+utcDate);

//Begin SHA-256 Encryption
hash = CryptoJS.SHA256(assemble).toString();
encryption = (hash.toString(CryptoJS.enc.Hex));
postman.setEnvironmentVariable("X-Signature", encryption);

so I am using Laravel to have the authentication and here is my code:

    $client = new \GuzzleHttp\Client();


    $apiKey = "apiXXXXXXX";
    $secret = "seceretXXXXX";

    $assemble = $apiKey . $secret . Carbon::now()->timestamp;

    // $hash = Hash::make($assemble);
    $hash =  base64_encode(hash('sha512', $assemble));


    $headers = [
        'Content-Type' => 'application/json',
        'Accept' => 'application/json',
        'Api-key' => $apiKey,
        'X-Signature' => $$hash,
    ];

    $apiURL = 'https://api.test.hotelbeds.com/hotel-api/1.0/status';

    $res = $client->request('GET', $apiURL, [
        'headers' => $headers,
        'json' => [
            "data" => [
                "type" => "flight-offers-pricing",
            ]
        ],
    ]);

    $statusCode = $res->getStatusCode();
    $responseBody = json_decode($res->getBody(), true);

    dd($responseBody);

but I get the following error Client error: GET https://api.test.hotelbeds.com/hotel-api/1.0/status resulted in a `400 Bad Request

so how do send the API Key and the X-Signature, a SHA256 hash in Hex format calculated from the API key, the secret plus current timestamps in seconds

solved the problem and here is the new code

$client = new \GuzzleHttp\Client();

    $apiKey = "apixxxxxx";
    $secret = "secxxxxxx";

    // Signature is generated by SHA256 (Api-Key + Shared Secret + Timestamp (in seconds))
    $signature = hash("sha256", $apiKey . $secret . time());

    $headers = [
        'Content-Type' => 'application/json',
        'Accept' => 'application/json',
        'Api-key' => $apiKey,
        'X-Signature' => $signature,
    ];

    $apiURL = 'https://api.test.hotelbeds.com/hotel-api/1.0/status';

    $res = $client->request('GET', $apiURL, [
        'headers' => $headers,
    ]);

    $statusCode = $res->getStatusCode();
    $responseBody = json_decode($res->getBody(), true);

    return $responseBody;