SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '391b2ed0689871c5f675d3f5257a5977d93f977eba1387fdc13e5d04f8f17bc2' 
  AND token = 'KXrzc5KbxmuNgRIiA5PtE4AzR7KqwHWtEpEbROOpARs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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