SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eb8f1c786d473d3193a6c2d319e226b7206d3a614e15fdcad0822ded30947b36' 
  AND token = 'adUwHjBOkhMr/kZdjCy1gGG1HSuI9P4iFPDGmv/5ECY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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