SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a6711cf951d47355a6f8827cb1b4094ecdbbbb95d564efe1b3b822f966891a0' 
  AND token = 'A+m3X5aUVUlcy7O5Lf9NPCq3B9ax9xdiRDxNZbmCjt0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

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