SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd7c85c0912d4fad965583c22fd256d0642cd0308fae1622be9c263a84e83bb6d' 
  AND token = 'R3kWrvu9LGluryUNN6M1NBXplUMmfEwj4gwwUznK7JY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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