SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8254b1d77bf6681c306a35513265f28686f9d775d02a73395283a83fb7e1d395' 
  AND token = 'V/xBk2p1YqzBYU7NAe9AqbA0GuY6YRcivrUa1BlNCtA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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