SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8be98d5cf590aa9fb78d08fb76c76b9d784af7b76f59d9304cb622e36709e2a' 
  AND token = 'dl0aKiy1QUlubo+Z+3cEhjEcL2l+LzBjsGOiYPGKmzA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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