SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3847b8638e0f39bd4df2d4091ef204ee6173eb35b6ba79397f3ac6d2c60114e1' 
  AND token = 'pIzepkbPM61VbUJAjspSyZMdfucS64aztTDS7ZPkEAk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}