SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7de88bb7084cbe233b3b7d09a4488632210e11974af1bfaf60d4e9c34adb0ede' 
  AND token = '4nZnRRAB0/RibVhLyLCTbzJbM5PXshymD4bpLY3Je14=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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