SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a10cba611399b733b978b0d1211f7e1a5de5432e49eb9435a535489334b0de9c' 
  AND token = 'pC+LxKGF+F4RPdvVkK43+wNO0NnZgDeK/qizdG5KVpY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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