SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1816a26bca468c69fb421900a410314d3cb8ddf8fbff61352b6024bc076126fd' 
  AND token = 'uSKbZQ4/Xr54WSOo820x7i3S7otYs4+wgDlRJZV9nP0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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