SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52e98df82453feb96f705e0a2fb7a9fcdf979fcb027d6d4a32bdae0339d26356' 
  AND token = '3KurSivJBwVXrFsTesVVNnSSmk1ViBluOJsqAbiFPqM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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