SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e2d1979a8e42700952465b85e932457327871605aca619daac99386f544a5dc8' 
  AND token = 're+YAssvdNTowQuxhyF9OHxnYEUiDt629fcul2NCj44=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00008

JSON explain

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