SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2f70f339796c3d6311039e8d251de2669a608af4be641548936a7b6f39af7444' 
  AND token = 'YJwjul+f/JdHOt/1KJBtMkrjOhIa8MkCcHZ2eRLz+Co=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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