SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '021a410320ace3c02324a34c5c936301be4948b5dbae542d25165597b9aaaf95' 
  AND token = 'HChxAY2j5OD5bYlhEPKqBEajhkeujyoSuKznQwLcXAY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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