SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3ce9bc70018e8807eccc8fe710e49155772d71f231f6e5533770411845be42f' 
  AND token = 'McCLo1a55V9iOWY1WpnPsAtzTMfj0eZfeQj7QNq2H24=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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