SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '7ab9fb4b8f99aac6c62cfdcb289bd7e071744210347a04b80f52021472c46593' 
  AND token = 'aUE60rLYD8BUmUxGsd/slsh79SKQ7sH7/nacrSwWO+Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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