SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e1c318ff32ea24489b40c7c03f4a4beddb798973f4a421d3913849c9db69bfff' 
  AND token = 'tn0UcaapSFSlVBcElkkYBrpKXPus4kJYD2hPxE8kYDo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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