SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '66ffb6facba4ae19319f9bf627512b1c23904523737756a0d8cfb6f1bfd4d0da' 
  AND token = 'CrYqpFJd8cLxqC/YGbzRtqK+vFpM75YVqSdTu/mECcs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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