SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e5ee9a6a908b7c735295afad3ab8364e7943afbe7af03ebc04e589becde0329a' 
  AND token = 'xO32mcYFjBZtW/eDfM6+Tqibx0obrNQdBFJANcP2FUs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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