SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2d3bb29d7eeedad4133b3aaac8290d1f951a6a6d542712da36f026ca32ae482f' 
  AND token = 'Q8MlMRvRdXCLofXV3GQ9oSkVOKN3JEj+a2JdwRZIeoQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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