SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8cadf98cc44f856b27de189448e1a5023215a983199fb2b998716a394f1926c' 
  AND token = 'o3BgYz6HhiKX+owF6L6KTWfXXKVMBdGkB9hcBaIaXxw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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