SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81b19d4869822c8f1d69b10ac543bf2769e59e03600aeca9cf8ae79f035ccb3b' 
  AND token = '2KGo1rYz1Lb/CWGIjmpNnzmYbq/wVAxpFi7ByIeYZTg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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