SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dcf732dbe448ebf0ac267f8750ad40e472c88a3d41e13584ce8c646cdbbaa157' 
  AND token = 'llcbL4IeWo5jqcmg7dAYlyGFETxpI/3UkgMlZNnV5pA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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