SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c887aea3cb0949a786e8bada3201294a89747aacede69e03316688d924390100' 
  AND token = '/zB/K8BHSWXe/g4WQfbgRoYvpazzP9IfqVyy/+hpozY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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