SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'a5d92c97766a530534aca3cf49180b67ef14141682fc4681499123129837d4b6' 
  AND token = 'qSPdCmdvleMDiK1FDkVp7+Bs5YIgXMBmZ3ocXbvpBng=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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