SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad16ff844ce0de3b01824b224831d30d9bb052ce6ff120e49436e75db7cb8fa4' 
  AND token = 'L9+JoSg1wAjbdm3mKhVrGAQhrmtlFYzF0E/UsPuQbuM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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