SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3393df19360468fed1249a7e6e778b4ca24b29ebe4121ae4a74078630ad426d5' 
  AND token = 'yE6wS9zR5FSXXBZySOzcYI8Gg3Yi0+Y7i6MhzWmFSrg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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