SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '231fdbe614433f5883a86de330c14537db85c230788fc913bc545a85b9bcf0fc' 
  AND token = 'kpT+g3R5fl+PnA9Ee4mov43avdFDdXRXT3xdRnHvupU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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