SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c121049bd96fe146b4ab41e16b487122b3fb474c0bb51ba263ee8bd273bd2576' 
  AND token = 'bdvgHvholIfFrYMMZJK0kxAuY4KVCwoSLvz9baluJmE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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