SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f50751cc2e9006f18fdc5f11baa23a9e724aca8674993cd7b274147c512cc7fe' 
  AND token = 'gsNy1AmDElvsBO0d1IkcOVFs+64sEyAETL/djN+T0IU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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