SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0ff4ab36ae930778baf365be4fb43f5f86953b623974c232484e73fbeabb7f3d' 
  AND token = 'S8LJoxpnMkKXEpBCyzFM143gxF53NGblF7cCCPQ6rX4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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