SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2f170c1dde3621891455bc0c3467c978cdf7da2b6579895feac092b34659f206' 
  AND token = 'xj1evQgJYEzWWALMKLIyQVM0yHeCouY6XusnxFAK1hU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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