### Description

The [Get API key information API](https://www.elastic.co/guide/en/elasticsearch/reference/master/security-api-get-api-key.html) can currently filter the returned keys by:
 * key id/name
 * keys owned by the calling user
 * keys owned by other users, by `realm_name` and `username`

Irrespective of the filtering used, both invalidated and expired (but not yet deleted) keys will be included in the response.
In the response, keys have the `invalidated` boolean property, as well as the `expiration` property that contains the UNIX timestamp past of which the key is no longer valid for authentication.

I propose we introduce a way for the API to support retrieving:
* only valid API keys (not return invalidated keys) - using a boolean request parameter
* keys not expired before a certain timestamp - using a timestamp parameter that defaults to "now" - also note that keys' experiation date is always checked against the local node's clock
x-pack/plugin/security/src/main/java/org/elasticsearch/xpack/security/authc/ApiKeyService.java
}
        }
    }
    
    CachedApiKeyHashResult getFromCache(String id) {
        return apiKeyAuthCache == null ? null : apiKeyAuthCache.get(id).result();
    }
    
    Cache<String, ListenableFuture<CachedApiKeyHashResult>> getApiKeyAuthCache() {
        return apiKeyAuthCache;
    }
    
    Cache<String, CachedApiKeyDoc> getDocCache() {
        return apiKeyDocCache == null ? null : apiKeyDocCache.docCache;
    }
    
    Cache<String, BytesReference> getRoleDescriptorsBytesCache() {
        return apiKeyDocCache == null ? null : apiKeyDocCache.roleDescriptorsBytesCache;
    }
    
    static void validateApiKeyTypeAndExpiration(
        ApiKeyDoc apiKeyDoc,
        ApiKeyCredentials credentials,
        Clock clock,
        ActionListener<AuthenticationResult<User>> listener
    ) {
        if (apiKeyDoc.type != credentials.expectedType) {
            listener.onResponse(
                AuthenticationResult.terminate(
                    Strings.format(