SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6496921a24e353037affa429e65a5fefe54a49d9204056294f3237c90581586' 
  AND token = 'Vv9IYaXcQQ33YgBaKo3TXNk5PQ6WfcU1dSWDnjrndWg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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