SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe98db8f89363df6b994d0707f74391f913a626e16cbdd8a457e221b63247544' 
  AND token = 'KOqCiCqWIygigvagpgeRnFjZD0SQ2OrznVQAdIhoyIQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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