SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c899b4f86d71273f7bba8d225eec9944d6fc3ddfda3fe86f37261dd08957af92' 
  AND token = 'TPmIkcmGOiQL+PYnwQ+k6Mhp9p2Godjk0VKKwJ7oeTM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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