SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f87b1dd248e06890c7e2e9476c1672b31e1500440bb30088695d001567205de4' 
  AND token = 'ytGskp4e7X/Gk+LLTsraFnWibRdq47kGgrEh8kyuO4o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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