SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '551691a87c04fdf946b19e744bbc103cb6c1b0a6f432fb0f50b819eed0cedbfd' 
  AND token = 'DllTslz4Hi1DIvfz9yXRz+DO+9vSrhjUiKANlzuo1d0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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