SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71734a874aaadd3f2d688db773b62adaaacd412e82996dfd1460e0741f16717f' 
  AND token = '/frDAibSy2UqlksQ3liKZHs1hxpwKE865s95e///reI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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