SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3341795c3363d99a79114a83eda121c515648add65bb380f162b543bcda2325c' 
  AND token = '/OYWZo9jKDrGLi/MGXV43v3A9zYgx5IWpbZ0tpIaj3Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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