SCP Foundation

Firstly, I have to ask, have you actually done any research on drugs - specifically LSD - at all? Because your SCP article seems broadly ignorant of the subject, and research on such a thing - even for a fictional article - is essential. If you want to pursue this idea, I suggest you read non-biased reports on LSD, as well as peoples' experiences whilst using the drug.

Object Class: Euclid

Why is it Euclid? Object class is mainly - though not totally - based on how easily it can be contained. This key seems very easy to contain; put it in a locker, lock it, done. To that end -

SCP-XXXX is contained in a standard containment cell

Why is it in a 'standard containment cell'? A 'cell' normally refers to a space big enough to keep a humanoid SCP object. It's a key; as above, put it in a 'standard secure locker' and secure it, and it appears it will be fine on its own.

Monitoring is to take place for at least 1 hour.

Do you mean 'monitoring is to take place at least once an hour', or 'monitoring is to take place for at least an hour at a time'? If so, why for either of them? It seems to be a static key that doesn't go anywhere or do anything. If anything, in fact, you seem to be risking people being contaminated by the SCP object by exposure to it increasing the chance of accidental physical contact.

Attempts to open a door with SCP-XXXX have resulted with no anomalous effects.

I personally feel this doesn't need to be said unless the opposite is true, and therefore people need to be warned off trying to open any door with the key.

the victim will begin to experience a feeling of relaxation

How do the subjects ('subject' is slightly better to use than victim in this case) describe this feeling of 'relaxation'? Relaxation, much like stress, is different for different people. You could give examples of what subjects have said, or you could give a test log exploring what one person experienced after touching this key.

Victims begin to hallucinate

Aren't they already hallucinating? I appreciate that they physically disappear from view, but who's to say if what they're seeing already is real or not, so that 'begin to hallucinate' bit doesn't really fit in. Maybe something like 'it is unknown if the area the subject is transported to is part of a larger hallucination, as subjects report further hallucinations whilst within SCP-XXXX-1'.

have double vision and have slightly distorted vision similar to that of LSD

I had a quick look on official websites that write about the side effects of LSD (rather than anecdotal experiences) and none of them listed double vision and/or slightly distorted vision - I'm not sure what the difference is here anyway - as a side effect. This is the main website I used for research on this. I know you've written it's similar to LSD, not the same, but it feels like an attempt to shoe-horn a drug into this situation when it doesn't need to be in there.

After 5 minutes, the victim will hallucinate

As the victim is already hallucinating, I feel this could be better written to explain that they are now hallucinating the key. What do subjects describe hallucinating prior to this, anyway? This is why examples and/or test logs would be helpful, as the reader has no idea what the subject is seeing.

SCP-XXXX victims begin to experience feelings of depression, relaxation, and happiness, and will feel "high".

All these are subjective. How do they display this? What do they say? How are they experiencing both depression and happiness at the same time? Or do you mean it changes - and if so, how often? Feeling 'high' just isn't really a feeling, or at least not one that can be pinned down by using the term 'high' - some people feel great, some people feel sick, some people feel dizzy, other people feel giddy; what exactly do you mean by this subjective term?

hallucinations in which all life forms are deformed.

Again, examples of this would be useful for the reader.

All in all, I have to say this isn't a particularly interesting SCP object. I can see you've put effort in, trying to tell a story and have meaningful effects, but it comes across as heavy-handed and also use subjective words with no examples as to what they actually mean. What's the actual story behind this thing? Why does it exist? Who made it? Where was it found? What happened before it was found?