SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0fa3e2683df6f0063cef9d769c14e826a70d30534fd4d5fe7ed57de36333b3f1' 
  AND token = 'N6FvjqZ32QmBc0QMlVifAo+len8vXWmzan2szaRM2WI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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