SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1f4750d98487b902e0494598eee36065d68e2c43bda1161ad2292315277f893e' 
  AND token = 'wJ+JXuf8+Gq8WJzuOGAzAEeHMHlNwLwpPRouGCh52As=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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