SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '45461aca85a5cd33bda1ad1bf21e3f062f65af9b042b5e0f6d894b3359625040' 
  AND token = 'XKJSXsFCL5a+ZNAE6mhFy9kqzwV9hgSeDP0v+g/MCBE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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