SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '534b413c15170baab06a43dc572500fe6d1411aa82b1698e57aa1353c91e39df' 
  AND token = 'SL0xMce/sWGb8JpYd/fzhoSKTbCUmdXvdxNBsuA8a2I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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