SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '00f3340b4ebf539229caa1084815b322926c82af103e9cfcd2eebde5a115f5a6' 
  AND token = 'ruudz+3RZDbqRe0SlCGpd/JpVSylgNV6cDBT5oxnwHg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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