SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '8236b0966bf103d90edf3e439d377959878e4609892ba0fb0db1a12d628e6255' 
  AND token = 'SnS3RMeI8tnFuteYEIFQqjwjXEUQSscX1KjRpkf3Pdo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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