SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3928bd0b29a42e7fb00f9d762b20167fc4f7bde2b320a23868a3ea47daf08de6' 
  AND token = 'F+1RwQZHRu8Nv+q1lNsijWXR+QLxIyhFU5/YNpEQm7c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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