SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '2608a9ebbc725017a36f6e513e5afe523f9ec3680e6e5d0881e3992b6cb307d6' 
  AND token = 'OjssJOoy1ntjODyfRiJM4fL8tJ7MS9jqlZ82RhhnnyA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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