SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3fe3ad47bc5e6d58644281d90c5ab578ee485663f6fcae359456dd68d349ebf' 
  AND token = 'pLyuMWWVrNdXCOaroTqJd7Q01lN3rkpLW2ikAz85pr4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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