SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0f71c6beb6d3e3141d55b64d1da76c8335adece4076648e7db4a8357e51d2d74' 
  AND token = '65anORYkldv2zbRC61nSbHg3MJpdSqvhdO9qAJGKmjc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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