SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '57e0910113486d3093afbec4c5237cfced7535e6403c2f63caf74b7ff570a1a9' 
  AND token = 'r2xfhtpHJSicjPG6HfZT2pOg1zJMIuMzCsJT/YT2JsI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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