SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'efc3e5a1e87045b98ec9962cbe59ce70ade74862848f3f0c73af9ab5d9e4906a' 
  AND token = 'B+oXwWRxYqEHuwzoM1GzLVK29g5k8bjedavzCvJ+8AI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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