### 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boolean property, as well as the `expiration` property that contains the UNIX timestamp past of which the key is no longer valid for authentication.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
return false;
        }
        GetApiKeyRequest that = (GetApiKeyRequest) o;
        return ownedByAuthenticatedUser == that.ownedByAuthenticatedUser
            && Objects.equals(realmName, that.realmName)
            && Objects.equals(userName, that.userName)
            && Objects.equals(apiKeyId, that.apiKeyId)
            && Objects.equals(apiKeyName, that.apiKeyName)
            && withLimitedBy == that.withLimitedBy;
    }
    @Override
    public int hashCode() {
        return Objects.hash(realmName, userName, apiKeyId, apiKeyName, ownedByAuthenticatedUser, withLimitedBy);
    }
    public static Builder builder() {
        return new Builder();
    }
    public static class Builder {
        private String realmName = null;
        private String userName = null;
        private String apiKeyId = null;
        private String apiKeyName = null;
        private boolean ownedByAuthenticatedUser = false;
        private boolean withLimitedBy = false;
        public Builder realmName(String realmName) {
            this.realmName = realmName;
            return this;
        }
        public Builder userName(String userName) {
            this.userName = userName;