SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fda3dd5764525b49ca83c7c9c50529671de7d3d0aff013d1567036849034f4ae' 
  AND token = 'DD3kjjfObhC1QU7BPX/JPfwIuCbrijRVgnauYilj4ls=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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