SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '78276e9df5bdc48ade1aa477331639d5bfa355cddd8a8b79299ad083fb5a987a' 
  AND token = 'XlLbUy3lw3eRdRYVAZYkK1eJ/PIFZK29Ir4gvqWO3nA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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