SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76a28f6a57dc5564b23af8828a1fd56b89b25dc1b1c87764173a7240be42d99c' 
  AND token = '/LiDgNl4R1FoPGwP5GFuhJ+7LeLvk+PyHS6pHNozXDU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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