SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c59028651849d6344af482c84da0e0aa9847955a92756312f836a6cb91aee775' 
  AND token = 'l7bO5ocrtKpbcJy5q/cTBeQb8D90Mv9LrKVU7w60ejo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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