SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c35cce1ef24995342fa4a436a1173fc192b20b23e7321bf387a97a820b02e33' 
  AND token = 'NxEDKDmrrNP2B+AVejkwpJ6KsAk8kmXqAYl8uc0cOa4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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