SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0e57673077bbc6eec2759788e57c38a864891b2db35661324abe720a393107a9' 
  AND token = 'S71APfEgoL+FT/AKOFRSlhGBkuozfIQmWW/a4SdWjD8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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