SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6dbc4298e7fe1116a2e9030b9d6a7b9aa6a4264cc4d71cdec7de55e38aeeb93a' 
  AND token = 'JZmRMg7mKpMzxf8yL47mQD2v7eOy1TMuvaSymQ8nY8w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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