SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '79f9e46136c81aee1f3e00b88b4eacd5a1a4cbd21af6d51b0534f354da586bfc' 
  AND token = 'fjbYEL5z3gUEwLvTLBcIOGE0nqiQEaouva2TUKR8J6k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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