### 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boolean property, as well as the `expiration` property that contains the UNIX timestamp past of which the key is no longer valid for authentication.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/core/src/main/java/org/elasticsearch/xpack/core/security/action/apikey/GetApiKeyRequest.java
}
    public String getUserName() {
        return userName;
    }
    public String getApiKeyId() {
        return apiKeyId;
    }
    public String getApiKeyName() {
        return apiKeyName;
    }
    public boolean ownedByAuthenticatedUser() {
        return ownedByAuthenticatedUser;
    }
    public boolean withLimitedBy() {
        return withLimitedBy;
    }
    @Override
    public ActionRequestValidationException validate() {
        ActionRequestValidationException validationException = null;
        if (Strings.hasText(apiKeyId) || Strings.hasText(apiKeyName)) {
            if (Strings.hasText(realmName) || Strings.hasText(userName)) {
                validationException = addValidationError(
                    "username or realm name must not be specified when the api key id or api key name is specified",
                    validationException
                );
            }
        }
        if (ownedByAuthenticatedUser) {
            if (Strings.hasText(realmName) || Strings.hasText(userName)) {
                validationException = addValidationError(