SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18a81f2f359929f92f8312b04e6567ca450635465bc05702b05664e3bfbd8da1' 
  AND token = 'cZG5mPCPDh9Ql7ugSeVlHfxvA/HjQ4HFaYJqYNXkoYo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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