SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9e76979e23639345b1ab0ccaa65a94b6b2f68fa5a2ada4d40a8915c4153827f' 
  AND token = 'wLvh2G37nxdtDfB+1mq7jFQP1NledYAitpTzOmHQJPM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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