SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4af87c77fdfaf435cadeccf19826e926388a7b0c3fa7eaecd56cd17391b9fafc' 
  AND token = '+shkkxftnHnas0Vhrvxf+mRWj6ipkCbd2x9fWUYpCiQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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