SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a68bde88507813af8af1fec789d8415d0036a90c2e5d6f639912bad47627d2b3' 
  AND token = 'mB16dFyI7HSVe7vFjhTbOeUipkJzXoxO1JDIi3mn0is=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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