SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b62d2812c34d8d0c77f812484d9143a913f5d85a56a4f5f3b46f13d4d234b363' 
  AND token = 'N84j3uR44RrBb/5SK4Z3MQHh4ectuuUiMdNwclg0aac=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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