SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b542ca9d00be9081c6b72cd6c12836312bd4c420846678183cdbb915770a70bf' 
  AND token = 'JN/AgoOWw9JsGMXCbbqU7rM4ItVcw98ZVfSFhXXVGdE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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