SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ac5be33e39149948caeb645c2b3012b26f04e169922f0a5bb57de32502d1e7f' 
  AND token = 'Kvh3lNT/FixBMq7+xqjFEmGXQqiduBla39kkXvoznOc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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