SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '17aa23da4f5353c378211f1aa25a4d6f2d202a7d42b7792e90e0313c4d9391da' 
  AND token = 'lqKmIa+GhUwCj5RmkwmQfm4jMfV8R758AGhJjRCQ68Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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