SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f3836008535bdcd1ca1fcda5b5941942ca0d1e8ec7e56be925ede615ff827294' 
  AND token = 'CyfpzxzsMg/83C4qw2slhG7lx6g/+D/4iPR1Fw7LiJw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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