SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9354e76f1df2b127ad78c07cf17ecacaf42b80cc3a6bfdc541afd448e83a9c1b' 
  AND token = 'lwAt6qGQHExAzJRhapyuvJ4OqC8OF42Ks/G0kgpmt0Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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