SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8b0aaaf2f3677e8c13639d42a7c38924e1ca0a204b32c99e774579e49c738ac' 
  AND token = 'uoFVOJ+1pxcwvgi+WEZj1ZJmhkppRc2YxnlTGkLQ7WQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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