SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4cb52b7afe18055b1242e0efdbe2778d5c42f65f2a4bda9d9087f6570db33350' 
  AND token = 'YXt1VhxqYpO9Y3Z5gVU5C32CxJx/kCjBhn9+MLgK1X0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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