SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c18518b211e76528bffaea528afd51b97dc65c0c506f1e23c7c5dbb979a161b7' 
  AND token = 'qOFngDPVSi6muECoauEQDkzsz5cMGV6cq7VuXzZnnDo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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