SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '86631e51328bbc586ef58f4042baa61c3bb3acc4432f45d96b1c7cd79a17467d' 
  AND token = 'y+GqsKfHmYIA+4L0NkzMd6WBiCTIU/NbYBi5MAHwHkw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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