SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '515c53f72b915407e2a037e6dc3937d9d7ae64c238978c18b008f987b880d03a' 
  AND token = '0pMyhqG//DkpgIctWJGYucQos2bH4OXxWo7nqzuL5Q0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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