SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd38eae98284b5066ee409b9bf14a72e9a0398b5542e263a25b81b81ce3da9838' 
  AND token = 'rr3lH4xf2VhzzXaqrubjdxYyRXUv+Pq+j9U2Wg/gpNw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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