SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '576ba410c393ed62444e8a68213fb04e231ddf53438d578e5584905b962d6d4d' 
  AND token = 'duvkvryTgVKPZlqbSqWOpOiR7GKx1MNUhQk+USnY1hA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00507

JSON explain

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