SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '821032272b773844811d7ba7d347af6904842ed2483302fdb565ac59450b0045' 
  AND token = '7Fl00AlPvC3MZoa0qXw5oXYtoQNushoU2wiphLoKTuo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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