SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '038420988cfd5d603ee83bb1fe5b77b308ad95da63424dd755420e2a01f97586' 
  AND token = 'Sh5cfPgZCsXtOAbeNHJ2L/kBarF7txx2ucCB5wMln8Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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