SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5012a1185510b190e6ba64206216aa02808155883653498b238c895ee6fe238f' 
  AND token = 'bvQexM8Su2L9/yOsSxLYYI5hknPPZWxwBjJeyNXdnXc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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