SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '383e6238aaacaa089eec4a1d6738749cbbfda4270123386b3f6d4d7696a19e6b' 
  AND token = 'nZs+WnUKW4fkoFsMEhcmiKYx8Ij8rqMBRADAByjLhKs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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