SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '439bd2acaf5bd597420a39eed115f454d58bb6a491d11d60de31fc63409a3224' 
  AND token = 'GSyhpNrOcy2aFZddCyuAKDFwTNArHqZusIJcwtlQVHY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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