SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6cab667228720f9e4a6965151e4f875e04f1f632354db7adc755d51e1561b29f' 
  AND token = '8G30jARRvoeQAZ4aFgUR+OyC22w3LgFYSQm7SpezD/s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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