SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fdf2690ec0fc3e72f7a72bc465597377dd496b790820abef01b49ff66089da11' 
  AND token = '5acFChXSy+msL0ZgqkVViLP6wuRcL6ZmYfvMlODj9Dw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00054

JSON explain

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