SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1084797d98a3b2b91f6f2b8d56e9ff8c417b2b3790ba65dc06aebfe1effe5e90' 
  AND token = 'aFCMWGtgROVWB/oAYoOzv+d3dTYu34FbUs439ZRlMhQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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