SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7991d87ee066f491cc2ae4bbbd28066201aca38bef1a47dc6040a5fff10d5ea4' 
  AND token = '/9oBbabISuL2xjpidzSScYZPSTCq4OqtwwRTdj+3Bqk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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