SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4a2fd14daf8a59380199d23a172438e5bab7bca389ce80215fd702c4cb07f9f' 
  AND token = '23e/Fqj+abZoP3vhur7YvXOcSzx7Mvq7g+RqT8TPIYo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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