SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c50fc38ed900ff492bd7e9c724747f021915437dd2dced7df54727ae59690cc' 
  AND token = '9RJCIg0somnK84ep40HMhNl1JZakriBFP2yj3Qvls4A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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