SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5be9635bfb5a396187fe28769275d5a337089c94be4a1f0403dc95c03b1cfc29' 
  AND token = 'DukQGqA+LToq5BVLO5MBxo//TdfJQ3pltYHUw6TZhiw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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