SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31936420fea1427dc127a909f912d446489ed90a25c3ed00925b216fd1a087a9' 
  AND token = 'akNG7r5LAw4zk0HBCFVzh5osW+pOXH6wSUhCGXD2ANI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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