SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b42cd088ada2dae0dab498689583a13d48c950b53a9036c175d6392659ecbd46' 
  AND token = 'MOFG0ak2FXdThww0e9F7KDLEjHSjyDGCzmwgBGwJHBI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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