SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'fe52bb0fe76da50427a9aa3e9369f217be3cedd4ec49694888bb7c86906b8478' 
  AND token = '0PDhcnxGEZlPQXW5vGldrz8Vr6UhhlYGHQLPL7cJSHY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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