SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5d7ab65c06a4b034e244fe101cc04f5987aec42cca125a4f5ee6a95f5c524565' 
  AND token = 'btCfNjLxTWmsrKNH72IQl/RUdxOMw7q8PsWf912vZnA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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