SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '353dffd077766859eb1c7fe5480d908813c94fc3a4bf4dcd303e96461ee9c7bf' 
  AND token = 'sll1joNGK7nKWwqx4TsUDjUVQ3jf5dajMBz/6jOrLRo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}