SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '141b51bd2642bebc2857be8371737a675e3d1789bc7f3418e4d21397ab655f76' 
  AND token = 'DUw5nwiHUy+zH0FNEgsfUzpRii7Zk6MVhAIonkKMYiM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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