SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2f91d88aff406b6103b62b455be10f5a904f92c815b7083220e975eb23e7a1a9' 
  AND token = 'jUtBCekldBr/VMp0J4mtYpfwvqFFCZXyUOlfjf3pwFI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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