SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73a44790a45a8a807f8417fb41968b8ba8b37fa86e6191e853bea131b725fed4' 
  AND token = 'jeSpUIVZvPOcyn1+bywLlOjFOf/WisfHxDRyoB2KYZY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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