SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a9646185027fa1d30c41dd3ad19cb8f059e781b47e1195af9867e4b939080159' 
  AND token = '5/tQIONHgRDT0FiBjUD/oaw5KOYCu8NZWWKMrUzSgJk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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