SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83c362ca3f8d26deeadfccbaaa89af71fde87a1dd77b20365232449492a785c1' 
  AND token = 'W17tjys3xrDy6k7ZwrOclOHMMC500B2SH5ecgFWqp1k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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