SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '823b2d423800f000c27741d9491dccf9b64416e3306b13549d3cf547ebe07b94' 
  AND token = 'MGzuCPku8kPh59FBlitRldQJBjK44eIaQVtcFgKUtqM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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