SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5ebea342021f91973668c9f87e859ca24cfe593b69c8671fe63003d3237bb8a6' 
  AND token = 'dBrqLqlRcViqX+37uUvIfwZKnUWrmblgsSFro3GfrTg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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