SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '85f81441aef7078b624fbf3bd0267bcf555126ee364b66d2e856e5c17aeb7536' 
  AND token = 'j0obJr3mClEsIKbH6TbJyfAxjh8dDYo2rd1AZBF9UPc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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