SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6181d9ba2c67c3e92822322081f45c683f23f3ae8d5dff50556874ecff9592f' 
  AND token = '6xbSTDr5vu1ZvIaQaB1qt5nd1oyoy50LRQcU3kXSWgo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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