SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ac40e0af35912847f2181005fb5be4737db4a98f5775b8803dd582daf1d5bbc' 
  AND token = 'qBxjLHGfwCC1gLtwGWapzdjDKUGbJR/2/+UEaa9M5Fw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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