SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68cd28c383a1606470d4958497fee4427f08157bcce064f2d76074a74fdcbaff' 
  AND token = 'LkcdjKzRCsCC1Zim70nVduP6cJklqbqwLl9PAJ647wU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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