SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '764523546ef6c7417a672190b65f370c9dbcfad9ac8302b157df3ce65c8cba94' 
  AND token = 'JfDk/XcyKTWxQ+pRxWc+i5h7H2JKgBNFYqlEZM65/7U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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