SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35605fb6a75bf59e192e979ec61b91edfb1a721803f1476bec9a3b58f53a99f2' 
  AND token = 'eFSSleGYkZqpF5rNSqw2mXO44kzNFo9OALy29SiA6sI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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