SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9ba81d6e5caa3fab1539fc7c766e943d2e2b7aed85f856314038af8c2f56267b' 
  AND token = 'xKDRPx/JBPbqVlMHtUsIzuuGBPgiUwtxlfFKn0UGBNs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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