SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dcb56de69c57a67c37e804ca166b7210281f178cae8420b629ecf9ae17dba922' 
  AND token = 'u//W6TzinsRVY2NcyUYZQU6QZFLus+PjQR+ovoM9SEM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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