Then use a change node to move or set the payload object, Payload wil be attached as a query string to the url in this example
[{"id":"b55b432041f9355f","type":"inject","z":"b9860b4b9de8c8da","name":"","props":[{"p":"payload"},{"p":"test","v":"2","vt":"num"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"1","payloadType":"num","x":130,"y":1040,"wires":[["c28d519b053c6a7c"]]},{"id":"c28d519b053c6a7c","type":"change","z":"b9860b4b9de8c8da","name":"","rules":[{"t":"move","p":"payload","pt":"msg","to":"payload.var1","tot":"msg"},{"t":"set","p":"payload.var2","pt":"msg","to":"test","tot":"msg"}],"action":"","property":"","from":"","to":"","reg":false,"x":320,"y":1040,"wires":[["0ea5c4df1261a275"]]},{"id":"0ea5c4df1261a275","type":"http request","z":"b9860b4b9de8c8da","name":"","method":"GET","ret":"txt","paytoqs":"query","url":"http://subdomain.tld.de/set.php","tls":"","persist":false,"proxy":"","insecureHTTPParser":false,"authType":"","senderr":false,"headers":[],"x":510,"y":1060,"wires":[["674f72cc236a0785"]]},{"id":"674f72cc236a0785","type":"debug","z":"b9860b4b9de8c8da","name":"debug 287","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","statusVal":"","statusType":"auto","x":670,"y":1060,"wires":[]}]