Sandbox

SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '678f3b4672883deda6be0f9c492563f71e89b036711d237fa0fc38cee498cde8' 
  AND token = 'PSLmS9jDAAjjB8tgizx3cM3Wh0hOFPhjhGGM4UCqhZs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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