SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'adecaf2dd7647d48bd362b73bf2262dff8ed60dc3dfbc84b35e8cc15d28f5401' 
  AND token = 'Y8RubsbRHc/nPycTU7RaAzd6bCsi9+hRxRDwludLk4Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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