SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '77779eaa9b795f15243aca453b41448181ae5af3bf3748a8b64e3fc620d9cc32' 
  AND token = 'vHGdIhrocJhCNT/DfityyZtnv+IixkwAshuV5KpW+ic=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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