SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '49a87ef318ccd6ea96764a974db90d67264cfc0a19f4f83c3d12264f77b9a541' 
  AND token = 'duebNCKyiMvTpoUDmXQxVDtK6f6rXhDgvKO+VqGlv+s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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