SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '258e0a4d5799438b1f1cec3f5f294129f9116f1640f6f020383d359ec8fd2e30' 
  AND token = 'rldshTJbRuzwKhCexo7DEv3E543HnHfOy9RZPfsjjXg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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