SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9f3c94fe97a10405bdfa5889e32046e12846cacd60863939f7040c8f39944415' 
  AND token = 'o3ZGJDhgjyYjgzYdIvw0o4plaqgf4w++dGWjfgaQlwQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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