SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3dc33d4a84fd4afcab4161e01b4e1ee9caddbef92093c65b08332cde269da813' 
  AND token = 'x3oFJkbJyoWYWNBBjOFE194G/ULU47VvrxXPO0doAjI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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