SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5dd539e41ccb09936f3990224b35b0afe4191d33bf26121fcfbdccd6b5332840' 
  AND token = 'V1xfmwHMNQsxOfPT0CJOFhihRRbSzEQD8yjF7Rv3jZI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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