SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd39d73db66b1806def0c9c8a5947daece36ace2942e7c35b52b95e9a3bd052d7' 
  AND token = 'TqhDOwNUBmI99UjCXWJ8MQsmT7ObTCfYCjdzpnqEYj0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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