SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a894df91c5260eefd2994ed8960fe9b75e6d67dd5b136a697cd9c20af3731b4d' 
  AND token = 'bDWMM9upWmthc8dOZ3SL37VYGTUzlnwrseTBBgkzsOg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}