SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8bfa0ac34f067461913b9a86f3ccfab804d87f9104876c88d275a25210650131' 
  AND token = 'TmWdUWLFfBkd5CywPI5ymP24WwqfueOiVgnbfPQ/j5Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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