SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6bba855bab0927c56da391520392fc1e47c492270cb78a290ab9dde08ac86a3' 
  AND token = 'JkuR7CHqUtULbpvKAoieiPrKxZ9UOGmsBT4XwY/2EFE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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