SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6809613561b3fdb7b0e0a5de2e466c301a7881f099af8201021938eeb39b07d' 
  AND token = '6YThJpCKIQUXBf5+zoBEBI3F/lxO/kQ4PnmlrrhIW74=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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