SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0ef37ff9b5cb82b9be6d762589397087c941017b4750fdb9bcc4d2954e08f961' 
  AND token = '87TZQLBKecIvgmnfxSfWqnxzsjKADX/mgLQVpfAgO7Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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