SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '85ba36d1a0347c9e0b1fe2462a728a963e7ef0368fbdc14cabf9bb912858bd6f' 
  AND token = 'xU2oO+TCBz6CUWmjrU3UThCAgw9n6cwv8lWDZzYBPyc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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