SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a999b5f3117786b7817624aa4eb0cf2f638cc9d75d3396c7a63b73c5c8a4f464' 
  AND token = 'dJiDHqOsezbxeneBgiVk/S9bpwhHZ65ulJcBDIO9xnE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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