SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a0b7480a8b508f4f02a79224f12937709613b1f7e39ac25c0da6b5ed1e408fc4' 
  AND token = 'HFPmWvQcg4ryfJL/LFvYfBsu/i48AzIqQw6te9EhREo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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