SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6eeaa79054ebbbfd3dbaea6538fe2986568fcda4f8929ad384b9317e0c0f46af' 
  AND token = 'artwB9ufZOn3ICuzyulD3ya+dUO9h/hdJrezZyKzbFA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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