SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f4873bf263bd89364764cc7ec23b5bb2943dcac83d91a060dbb3aee2b44a761f' 
  AND token = 'lmKpvRtunQXFQAFuIMJ6jLFSAgihfwkG2/teXojcTDU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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