API Woocommerce GET function – SetOrder with variable URL

First of all I would like to say that I’m new to the programming world and that I will appreciate your help with my following question.
Basically I would like to add an API call as soon as an order is completed and being actually paid. So I found this function online.

add_action( 'woocommerce_payment_complete', 'my_api_call');
function my_api_call( $order_id ){

	// Order Setup Via WooCommerce

	$order = new WC_Order( $order_id );

	// Iterate Through Items

	$items = $order->get_items(); 
	foreach ( $items as $item ) {	

		// Store Product ID

	$product_id = $item['product_id'];
        $product = new WC_Product($item['product_id']);

        // Check for "API" Category and Run

        if ( has_term( 'api', 'product_cat', $product_id ) ) {

	       	$name		= $order->billing_first_name;
        	$surname	= $order->billing_last_name;
        	$email		= $order->billing_email;
	        $projectsku     = $product->get_sku(); 
        	$apikey 	= "KEY_GOES_HERE";

        	// API Callout to URL

        	$url = '##API URL##';

			$body = array(
				"Project"	=> $projectsku,
				"Name" 		=> $name,
				"Surname"  	=> $surname,
				"Email"		=> $email,
				"KEY"		=> $apikey
			);

			$response = wp_remote_post( $url, 
				array(
					'headers'   => array('Content-Type' => 'application/json; charset=utf-8'),
					'method'    => 'POST',
					'timeout' => 75,				    
					'body'		=> json_encode($body),
				)
			);

			$vars = json_decode($response['body'],true);
        	        
                        // API Response Stored as Post Meta

  			update_post_meta( $order_id, 'meta_message_'.$projectsku, $vars['message'] );
  			update_post_meta( $order_id, 'meta_link_'.$projectsku, $vars['link']);
  			update_post_meta( $order_id, 'did-this-run','yes'); // just there as a checker variable for me
        }

    }
}

In this function I would like to have a variable URL as the example below:

http://server_name/application_name/Myapi/Productslist/setOrder?DBContext=Default&purchase_no=2&order_no=2&barcode=5009736400011&ordQty=1&sellPrice=300.22&key=password

Which is a GET function in which the variables are:
purchase_no
order_no
barcode
ordQty
sellPrice

And “key” needs to be a fixed string.

So, do I need to add all the variables under array?

$url = '##API URL##';

			$body = array(
				"Project"	=> $projectsku,
				"Name" 		=> $name,
				"Surname"  	=> $surname,
				"Email"		=> $email,
				"KEY"		=> $apikey
			);

Moreover do I need to change the method to GET in order for it to work?

$response = wp_remote_post( $url, 
				array(
					'headers'   => array('Content-Type' => 'application/json; charset=utf-8'),
					'method'    => 'POST',
					'timeout' => 75,				    
					'body'		=> json_encode($body),
				)
			);

Thank you very much in advance!