SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21cf302e0283211195bb424b9ebe6e7ebd890285114640cc4738f257ff8cc6dc' 
  AND token = '/ZXDGn34He4OdpLJnFoHNu6hW6f3xvyBnVDYxJJsW9g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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