SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1d519c2889be003e08aa958c99b9e483500e42e5a16f8a2fa16be86b5c2fdef2' 
  AND token = 'YYAjgFpSpa+o+SbKId0ylhOzmM9JixVzFpflNIIrzA4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}