SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '79a97efe58a9eb02ad746fd199e387fb6540519a70bafa7b94e23b593cba3823' 
  AND token = 'vlovvnNGtO3jXOSPJAyftEGqluet5gTtVSlHhwxBN8A=' 
  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"
    }
  }
}