SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd50a30b9a5a5030c6ecd7f1d33b9ecf5d205e1ba37f98f984b5da7e5cd75b01a' 
  AND token = '5NelwQDxLcGmhu1YlMepeOiafdfVCFGIKareVw6EN5s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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