SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb23ce5e11e6e82331ddd0961effd1774b8d72c556d2b6e177ec677407a64836' 
  AND token = 'IhPqqnvQpiIU8oBnGWmyUqVr+f7rqPSKjOzTMObkArU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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