SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68bc506159e4c958857a6ef41eeaa63455104d2869712400f938435d9ba94b32' 
  AND token = 's8LGtdpMyv+uTWY9PAG2rBLUH4raenicyMu2vZqe9Ic=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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