Golden colour comes from using almost entirely the palest base malts available and keeping specialty grain additions minimal — there's no single "golden malt," it's a grain-bill strategy of restraint rather than one specific ingredient.
The palest base malts, and their real colour figures
Pilsner malt is the palest common base malt, typically 1.2-2°L, kilned more gently than any other base malt to preserve that minimal colour — the traditional foundation of golden and pale lager styles. Pale 2-Row runs close behind at 1.5-2°L, the standard American base malt and nearly as pale. Both sit meaningfully lighter than Vienna malt (3-4°L) or Munich malt (6-10°L+), which contribute a deliberate golden-to-amber character rather than the palest possible result.
A grain bill computed
4.3 kg of Pilsner malt at 1.6°L, with a small 0.2 kg addition of a slightly darker malt at 10°L for a touch of complexity, in a 19 L batch, computes to roughly 3.8 SRM — squarely in "pale gold/gold" territory. Check this exact grain bill. Notice there's very little colour headroom in a genuinely golden recipe — even a modest specialty-grain addition needs to stay small and pale-ish itself, since golden styles have almost no room to absorb a dark ingredient without moving out of range.
Why "golden" recipes stay almost entirely base malt
Unlike an amber or brown ale, where a meaningful specialty-grain percentage is part of the style's character, a genuinely golden beer's grain bill is typically 95%+ base malt by weight, with any specialty addition kept both small and itself pale — a touch of Vienna or a small percentage of flaked grain for body, rather than anything approaching crystal or roasted malt territory. Adding even a modest amount of a darker specialty grain (say, 40°L crystal) at a percentage that would be unremarkable in an amber ale recipe is enough to push a golden-targeted grain bill well out of range — see what SRM is an amber ale for how sensitive the mid-range colour bands are to exactly this kind of small percentage change.
What else affects the final colour beyond the grain bill itself
A recipe computed to land pale can still finish darker than planned through boil-driven darkening or mash pH effects the SRM calculator's Morey-equation formula doesn't model — see does a longer boil darken beer and why is my beer darker than expected if a genuinely pale-grain-bill recipe still comes out visibly darker than its computed SRM predicted.