SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e35fe45ae5f782ca92dcb75571fdb638f646aa3f0675ae1aaaf4afeb9cb2b3e' 
  AND token = 'LA/DEU+0GZyf1KOxc+qh8omvzubdF9wZ5m/cVgmkuo8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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