SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '518c375b66a12fad753b4478656c3575bc3b68e28b99b0c7bf8b83f27b8f9e85' 
  AND token = 'EYlzLpS0FAVTpZBj/u3WsQXTkvmZ753kwjiuUDmPfkk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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