SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7af6234a6741feedaea2bc0224bc61141ab10b93be7ecc40709e0712d77c0f9' 
  AND token = 'TKLNlUY+0TVMJrYxy13Z+urbB3h/1fn3G/qCAJn0UC8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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