SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '640dd226adca6a834350fc05617c1f6bcf6ada4942fea6ca685de91d89dbc20a' 
  AND token = 'mXTiOAWIICJGzSPtvVzt0sPND/wpvAqEEqte8cDAiJI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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