SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe8fefde98ae9ba5ad8d9af282e10988adba9da465cd1f28886606c81b145745' 
  AND token = 'aZzkCseurw45ikbsHtGHb33ZbPKmSCWkCavf/DzSjM4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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