SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '519291867f007539ac74ad9ce398b01be0e977fe7829cdab704c6eef37559fd9' 
  AND token = 'lVdCnNz8ONWf7MqjAbZc+1f1d6ohWGA//GgPfMP68ig=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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