SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0a66451a7182e54d6fe54a0aeeac589460dab155ebdbc7217d4f754557c7ce2e' 
  AND token = '9mhmm3sB9LXxBqCyELKMHkWAPIuWgjebOK2p4KMQw84=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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