SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'd9dff3cf259f5d5a036928c5953e86d8722d2e255ffdaaf6956e9e198ec84048' 
  AND token = 'cZnJQhEtz2oG23E1FKOoM3B2hPMtuMj3ohFttqL5vDs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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