SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a2d2f31da56f4545ef09767d3f6eebe03221a426c4cd87dc20257525cbbb996d' 
  AND token = '26PfW568szKYQmtcIPB/ApnPQhpAUxJTg/Xx4fzwuHY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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