SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9a56cc621517b48ae111f658d5031aa8c4e024b00001d921b360cf5d7c9afda6' 
  AND token = 't5FqK8rg1xMymOOOXo+kcd58ydyGeFfjJP4f2vi6fSA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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