SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c12381d70fe0ef8eff251db7a9d91fae0e401e77c3194254105c6863788b21f4' 
  AND token = '4U+7rdibzTxdpbOuXMAOTRD82owILLXfdWKUXrPMJx0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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