SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cf1683b333bd121b6fdf269e936f3caf14f5521f665a94535f61b20247b82ede' 
  AND token = 'MY1JEBlo4l/PKTXTOV6B/Ul5ImUAfpz++Vb2xx/DRJg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}