SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '49b8b1f309bbef64039975f538cf8e341b7efd3042f8930d19e9724363e0151a' 
  AND token = 'Vk70nEaasX+enMYnF9Vt3k52xIetEZbwZl9CHuxHqv4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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