SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73fcff8a28e511a8bd72c41b28fd1ee986ecc65509c786a0931b304d777f7a3a' 
  AND token = 'WST2ZtrBjFeuGjqO92A/ywEffuI+FtNQi2rd6M9iUlA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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