SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '181e2f4afcfe1a06d1ab6356bfe312a11fd976cc757dd4c5c5215d2b7ddc1c93' 
  AND token = 'ZcQgsWD899dLNKmHSqXmkD8/oeVKsuDPmm60FaC7tRI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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