SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '847d6734a6e73d53cb62e9ef2a15c0cb30d1e82a0c4f16ae1fa3dbe028c67673' 
  AND token = 'VmCdpD1EeTKcbm1BysFf8iIxca2srZ6PbgRwk8MNpLQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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