SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ae291300baf58f72db57e9410a30961e0e2150a7c2212c765807f5859f471421' 
  AND token = '16r+X0C0oG0xYUnoTPs4XtKLRWUvfe2bPcGavnbzseI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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