SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '358c9fbfecf648d1b375b6eecdb482b954ad5bb4613bedde6e1f4fde7240f546' 
  AND token = 'o+vjoF9ceEjmKT1uz5CvEmHbUtn8kwcKLnYePjr0kl8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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