SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '539fa10f5f10f785961454dce9b4dfdb0529b6463c542a435e229b65cc6754f3' 
  AND token = 'Xv1KG/73tZN7wQJZki3JYOLVu9dK99syeP0YZIvImh0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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