SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dbd8a7acf490496a697627c35764dfab91ac183ab9572545e716272548e20153' 
  AND token = '0ID5KCBcBt1pDjl8ZkZoPSGfHW9M3jYynMbOfMYYr2s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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