SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6297c817e29fded00c906df829665d9da5c1b625abf0d76dd2481a293d354266' 
  AND token = '6YpOgWV4dRoUETA39x4CSggXHpjxdHioUxSeVXm3n78=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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