SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fa5fb19847d7f05165995e39158e25b4a17b2821bbd17089957e15c062237e43' 
  AND token = '9u7/UmMZMckIZt9VlNUIpKLfd2xdqOaa4EVF6tYInCE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}