SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fee39b88311804dae47138bf768edc814590082ec574242f1da647de4cea0465' 
  AND token = 'M+UaSFd6Jzhm+ByGGldtDKqlXrfOITzol23WMsYpMw0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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