SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '188b4346c205d1cc8d1cc041e5a13125224af2611a895247aa9628f46379192c' 
  AND token = 'ztYb2hx+R5K5tK0KFdSwTYtxm7VBVY0jA/dPsIAyg/U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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