SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ccc2acbeb030d508792f347bfb00e603b72e43de62d5b9dabe53a45a7a6f47a' 
  AND token = 'nZ+RDqK8am9C8Vy1d6XIlfS51kMfTjyeer6rT4INoCg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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