SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3de3db3c515994085b26334a0a838724b62fe167c47cf74ad6bb4f55b4f615b2' 
  AND token = '1LNkdjaZD/NaqBVGCeJMP4xpXlGyw4JFtGVuMWqA2I8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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