SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21b64717116c518f3702b7a9f3dc13ed5efe10ce253eb1676bd6345bf64a8eb5' 
  AND token = 'E6bimAigAhpwuWja3iPDYIhjWgg1JP/fPaymgN/2Ecc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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