SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8cd6dd4c4178b1f363bed3f573692b1d0e9e976091a8403d34a165cc5d49369b' 
  AND token = 'QH3JktHZnZ/dPWvlNzfxmJbNY/zTywRP/h37WM3dPcQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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