Authenticate via api-key in chrome web store api - api

Question

I would like to automate chrome extension deployment and followed this guide for the most part: https://developer.chrome.com/webstore/using_webstore_api. I created a project in my developer console, activated the Chrome Web Store API. Next step is creating the right credentials. There are three different ones, when i let google help me choose it tells me that API-key is just fine to use for this API, so i did.
My question: How can i use this API-key to make API calls? I tried to include the key in the params as pointed out in the docs but that doesn't work. If this is the wrong approach i really don't understand, that these sort of authentication is suggested by the developer console.
As i try to automate things on a build server without using chrome or some other browser i cannot really use OAuth credentials.
curl \
-H "x-goog-api-version: 2" \
-H "Content-Length: 0" \
-H "Expect:" \
-X GET \
-v \
"https://www.googleapis.com/chromewebstore/v1.1/items/ITEM_ID?projection=draft&key=API_KEY"
results in
https://www.googleapis.com/chromewebstore/v1.1/items/ITEM_ID\?projection\=draft\&key\=API_KEY
* Trying 172.217.17.234...
* Connected to www.googleapis.com (172.217.17.234) port 443 (#0)
* TLS 1.2 connection using TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
* Server certificate: *.googleapis.com
* Server certificate: Google Internet Authority G2
* Server certificate: GeoTrust Global CA
> GET /chromewebstore/v1.1/items/ITEM_ID?projection=draft&key=API_KEY HTTP/1.1
> Host: www.googleapis.com
> User-Agent: curl/7.43.0
> Accept: */*
> x-goog-api-version: 2
> Content-Length: 0
>
< HTTP/1.1 401 Unauthorized
< Vary: X-Origin
< WWW-Authenticate: Bearer realm="https://accounts.google.com/"
< Content-Type: application/json; charset=UTF-8
< Date: Thu, 15 Sep 2016 14:14:18 GMT
< Expires: Thu, 15 Sep 2016 14:14:18 GMT
< Cache-Control: private, max-age=0
< X-Content-Type-Options: nosniff
< X-Frame-Options: SAMEORIGIN
< X-XSS-Protection: 1; mode=block
< Server: GSE
< Alt-Svc: quic=":443"; ma=2592000; v="36,35,34,33,32"
< Accept-Ranges: none
< Vary: Origin,Accept-Encoding
< Transfer-Encoding: chunked
<
* Connection #0 to host www.googleapis.com left intact
{"error":{"errors":[{"domain":"global","reason":"required","message":"Login Required","locationType":"header","location":"Authorization"}],"code":401,"message":"Login Required"}}
I also tried to set it as header but neither of these worked.