SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '57172cf740258c4dc67fa6c1fab6b7f93088b7b23469a6254c2588a39bc6008e' 
  AND token = '/MmnJtPIm6dGyXhwpzHXXYZtyTjOjhmVGxMGUNsFwGg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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