SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b945e9d27aa884c498f6a425181e78049e513316142e8de2810c26e9228305f' 
  AND token = 'U5UvLgUdULMC9E2A1pLm0N4hOGUljacTaa3bGeIRHQ0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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