SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ca6cd793157f4e0781e2565b956244f3e621f9c8a8d2695615793882d8486289' 
  AND token = 'vz2LftrYmJmaFBTAfYADrWBVnXiKgXmbKFxDygXevVo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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