SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3aa2da43be17472b880dc174a00af8bb408d22e2518f3964ede186cc0c319c0' 
  AND token = 'VZo0f/1QSe1xStHVfxJsTrsWXahtCR+wY8gwEmEVKNo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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