SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f434a00d3aca5233c1455d3d38f5925aab55434f44fbdee0860afaf8ad8f837' 
  AND token = 'IyWxSsS0f9MQ8q79MzRmd+O80LH3jVYM0U11usR8LSY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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