SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '800137326f224cf6f0aaeff3378abb029c6008731a999806bc6037f28345b933' 
  AND token = 'BIweJGD4HW9hQwjHQvWR2VUJd9k8PKNO5JvVA+KdyJo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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