SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75355a44495e7b6767f3d6831cc3c8b22b9c49e466f9ec491cb3ee69a1d3f696' 
  AND token = 'ypKpx8kZxYnEkQo+YqgTNXQGjElwqR7zfDTwnDcat4U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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