SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4892d61a996e064a6533ee34993ab16686251d656b6f179f381e976c653beee1' 
  AND token = 'DAIaFqW6JMKdXIWtOn8RRrc8zDWuYhwfhOlCCcmJ4og=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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