SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b76ee4fe6eb5940e20acf3f362f17c3646b4afbc5104a8c747c8144a3f8053c0' 
  AND token = 'wbnHH2MsISoILycq6gy7S94wP16Y6WwGx9RpL1WnRbA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00057

JSON explain

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