SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '98a8e756a8020d27370b353e2d989d55bfb845d16eef474a5b8810de7a7ca174' 
  AND token = 'svsJ3GCWahqD8ZTKxqQGuFZWsTTdL7wdrDtPBjbFXBg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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