SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9ac8194e2b7070af5b9c19b35b7c6bbc6aecabc939cb48a74ae6caf884716159' 
  AND token = 'uSix0RttxweP3ogvDNupmQ2RuS4sZ/INXihyPJyEYSg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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