SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ab3fa428699cd812ab66e823abd9ab9d1decab4804accc9754acb8eec7c6d80e' 
  AND token = 'sUlxw+TxVg0hcKN/UfUdDJAxVOH0nZj38vq/PbzpBkM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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