SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '780664bc470ddb920abbeafd141f67386c8f8db63e35e17a34b7e3ba2e246469' 
  AND token = 'uDPnRw6BPioBwKFSZLNYaE94KzK2UpJT/BTswGW8nqM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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