SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '832039f8ade345560974df39d04d21785b633a6980ecd3d5242d5bd9cba66c09' 
  AND token = '7QamKhFcqbRr9QxEmSJjpojBVPZJ0A9xQkMCoDzgHtI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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