SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9ca1ba90390de751d7fd7cda9dead434e38de26cddda3accbaf03a3562feb737' 
  AND token = 'D5SSk7i7+E1RuBlBTySiNYeFFhDt2fipHSFE4BI2gIs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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