SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '4a6b4281bb7bb6a98d34292bcf451669bd4ebaf37ba8ccf13f3e211977e09d56' 
  AND token = 'SbjqrPNCTil5YJ5CFgTr4ZLSpVXRkstxVfPzqhQmkug=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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