SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76ec55f9438bbafbd2bc209d3aa9a5dacc70394c10460344f9402dd5f6b24249' 
  AND token = 'XLRfrlTouZ6v4kXj+PJEByx6fx3Wns3gGEDn2g9EB78=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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