SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '09dfdf7edc988ce452fc32dc7f0e11a026472e6a635120d3917d13331d314df9' 
  AND token = 'YzQ5HHT+PdCxKnoGDZQNJd9aHqIm/yNxe5JwTQSgvhw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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