SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4dae1ae3fe69a2532aea70ff58c3d50e6d2006d7998d4fa688f0a99f378c854f' 
  AND token = 'sGzvtafj9Vceflm/umRsd511Kes0+qxnE2pLAesNA7Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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