SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a08afc18fd24da82fc09fefd040eed09b5c273a4e270f53f45cf8ae2238be7dc' 
  AND token = '2YQuoVJLZ16UxI+6JE4njGKUA0nwJxRMGllLxOSsXCM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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