SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2ce1baf6e608fcbf9fde34b981ac629c005584dc7b179eea64d1a9d2819ab035' 
  AND token = '5s/DhNJ3xS+0opYpOVLh7V5iUd61fSlzLvBhzwyrGDQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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