SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fdb2f52e5a7533e45bb642916b4c5d8d591651e5beebe5522c8fe7d55a68c708' 
  AND token = 'T3CpZedKoTmOjq/xW/sJiO2dxcApEaWCyE+Z1lXu0o8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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