SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81877e216009cf07864f933a6329b7a1f3dc81740551231286d677af0ea41f2b' 
  AND token = 'aRJwH//cqKm5PBY6MDGeMbQGALa9ziH2kjVKOlmHdc0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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