Sandbox

SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6fc92e487c29b3a54e7393fb8b661d068dc2b8eb3c4b6aed99c39caf34ee995' 
  AND token = 'sK4aqYLWiiN812qXs+Plh+HkF80FvUtgA2sgBZZ9y4Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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