SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3a35861871f810ccb9fbe3bed45eb8bf50d1e2ff9c68caca80ad0ebe0775a5f' 
  AND token = 'eoMrTg6WgdA0k30Xz6J1K8NPij/bF+etya5Md8ija14=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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