SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1919b5a83a32ed889ff651641473a19251276285278f2f17eebabd576d918642' 
  AND token = '4B/PydZmO4q+/ePBa9ZnuL0mRXX5GkZRlRwJjEg1uZ0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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