SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75c4a00dda476b276475cb08a66f3f12a96d42210e961e76f1eb8b575b93504c' 
  AND token = 'BDdCIGtChvBKpeMJCiWJZsH6JXIUP0DeRCKEbKDL0ps=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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