SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c52338d849c2a37983bd54ab467497e74f3516975083da260981804b73fe83d6' 
  AND token = 'vlwxbaX0DMQ8IJsxU+VvFKbJAGi612cq17nWskLhxGI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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