SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68a14002257a0469e8fb5154ad10aab916486560eddee218335f85f55cc4ff04' 
  AND token = 'Muq3GHMvYIThvzna6MHfY+QDdi9aBXSG+CSuyoDDN48=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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