SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '92aaa632847b8b798de9d36bc8e4f4e8ce6074a91d9b0e16354615b06a66071a' 
  AND token = 'Ns4g17OeLowJMkd1yKE2EspaGYukLWepE3nBBarwlzU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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