SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8355a411015aa38471f4ca7c698b70870442a960e0497f5616af9a171981ccb8' 
  AND token = 'WVwLwKqkL0UvGHCgqqeaWgBrsNaBsdUO04uoyFV/0GM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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