SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8e8e849ed65ed9b143551440fc0c839aea593d6b15a985106af543df02723386' 
  AND token = '9F6xlIn7DkWf12lBHBNS7QyHio4hgqdn3tejBga/Ypg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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