SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b74c100ef903f1cb7575cb95aa0ad56815c6abf9e878ab042a3242a1dbe1e8ca' 
  AND token = 'PpZiXEJIOY32rtKZTGkhAOGlyKs4E7h5VfKCi12Dl9g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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