SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '755639c280e8ee46163ec59dd5c3a816f195aa28d35a50c9f783419724ea8c9c' 
  AND token = 'VVILTW7dxToQq811iJkXC04HgxfOXyZIolAfL4KpChM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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