SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '3b3d6e891d2361dcfc4d12a9b0dc504380329403c22945eee86cf24a18373ee4' 
  AND token = '8tVQTfduTzKx0HYYJCKazzdGma55DvjXSntZ2eTSSTY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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