SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '5dbd2240bd301114cd316ceea875d7d4da8b36727d45b778abdd93be9bce5edc' 
  AND token = '/L/aIjhN8efZDYA11Ad64osDvoVgrcPCI1v0CbV5fto=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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