SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe8aaae76d371ebd5b3a77523c34f4d48f68defdf00452c2f7692c00b25ac705' 
  AND token = 'GcpyxLdPlNYgzl/8NoxYguXIiOcmwDT9xfLRUYyAT2Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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