SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '720f8e0482b502c180a827a9b3cd7de3735660713369f0ff801dfbc409d5e6e7' 
  AND token = 'FC6dRNNz5sAas3KiFefLEp5mNqmh9NTPekootTiMuXk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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