SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '96ecc94897b50e5777b0675e87d505c0d58d1b69135879c47416b91b0d31b02f' 
  AND token = 'cWKYcG6OoSSENP+1uW9er1CGLPAXGe/7XdPHt1j++Rg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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