SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1c46f8087198fdcce33469e9365b05077cf23b62a952d951dfbd910c72a1f9e6' 
  AND token = 'zKLJ9VB8niBPHEn/BrTZTpXxLX/FASvWTYxRG0uDN4k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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