SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7de08668df0a874b47960205446fc736f9cb246de0c9324b2b7fe600809d3e41' 
  AND token = 'JtzABVrY3uwnvuSZjmn7T+ivexIeMMnGxjJlMOUAN2c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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