SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b0aaf1c969f38615142682008f4d2703ac1e3c24db1d8f5023fe6b8219e7fa3' 
  AND token = 'EomrmmIJzDtRZTHeo9N/SJnBwDGaLIqkUg5GsNhq1lQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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