SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c1a24ed36ecee569147124017c957965a038dae29b5d8ff34f542013051a718c' 
  AND token = 'BvhHovlvz5RVS4sbHUxAxScmvHJNc82KiOBpCBA9umo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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