SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15b7945eb35da7fbbd9af0312348a05d6c3b5cfc1e8aabf5462ce3e4cb1583d2' 
  AND token = '7BwKN5+8hFvNNr7+nNuwsG7zh5yDIIXviC9DzR9jjUE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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