SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f3891eb1101c5e443b8c0249f707795a9c0dd4986d5696b9611597d9696bb1fc' 
  AND token = 'hUMPK/OF+kKBLV7SplDcWv1y//zOAAnNkaZBY+ezKLM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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